t6 da ban hanh chtiong trinh khung ciao tao Dudc si Dai hoc BO Y to to chfic bien soan tai lieu day — hoc cac mon hoc chuyen mon, co ban chuyen nganh theo chuong trinh tren nham Bing budc xay dung bo tai lieu day — hoc chuan v6 chuyen mon de dam bao chat Wong ciao tao nhan luc y tg Stich "Hod Dai Wong - vo cd Tap 2" duoc hien soan dila tren chuong trinh gido duc dai hoc cUa trtiong Dai hoc Dude Ha NOi, Bo Y to vdi phudng cham: kign thitc co ban, he th6ng; not dung chinh xdc, khoa hoc, cap nhat cac tign bO khoa hoc, ky" thuat hien dai va thiic tin Viet Nam Stich "Hod Dai Wong - vo co Tap 2" db." duoc bien soan bdi cac nha gido giau kinh nghiem va tam huygt cua truong dai hoc DUoc Ha NOi Stich "Hod Dai Wong - vo cd Tap 2" da ducic Hoi dOng chuyen mon tham dinh sach va tai lieu day — hoc cila BO Y t6 th'am dinh vao nam 2008 BO Y t6 ban hanh la tai lieu slat chua'n chuyen mon dg sti dung cho nganh giai doan hien Trong 411a trinh sii dung sach phai duoc chinh 1Y, 136 sung va cap nhat Bo Y to xin than cam cac Nha giao, cac chuyen gia caa trucing Dai hoc Duoc Ha NOi da clanh nhigu ding sic hoan clan sach, cam on GS Dam Trung Bao va PGS.TS NO Si Luong da phan bien de cu6n sach sdm hoan kip thai phuc vu cho tong tac dao tao nhan 1iic y tg Vi Ian dau xuat ban, thong toi mong nhan &toe y kign dung gop cua dOng nghiep, cac ban sinh vien va cac dOc gia d6 Ian xuat ban sau chtoc hoan thien hon VU KHOA HOC VA DAO TAO (5) LOI NOI IJAU Hod Dai dicing va Vo co la mon hoc co sei chuong trinh dao tao Dtioc si dai hoc Theo quy dinh cua khung chuong trinh, phdn 1ST thuyet Hod Dai ctiOng va Vo co dtioc giang day i3 hai hoc ky cUa nam ddu cho sinh vien Dtioc he chinh quy Mon hoc gem hoc phdn: Hoa Dai cuong - Vo co va Hod Dai cticing - Vo co Mei hoc plidn dtioc giang day met hoc kY De dap Ung yeu cat' chung ve nang cao chat Wong dao tao dai hoc va phuong phdp giang day tich cuc, chUng Cal hien soan giao trinh Hoa Dai dicing - Vo co theo htidng tao diet' kien cho sinh vien tii chit nhieu hdn hoc tap Theo do, nhfing kign thtic ciia khoa hod hoc chtoc sap xep, trinh bay met cach hop VT va he thong, vita co ban - hien dai, viia thigt thuc van dung, ke ca lien he \Ted kien tit& Sinh - Y - atioc hoc Muc tieu ciia mon hoc ma sinh vien can phai dat la: 1 Hieu va giai thich duoc cau tao va tinh chat cila cac he vat chat (nguyen tu, nguyen to, phan tU, ph& chat, vat the) nho nhang kign thlic cO ban nhat ye co hoc Wong 2 Xac dinh va ly giai duoc chieu hitting, gidi han cua cac qua trinh hoa hoc nhe van dung cac nguyen ly cita Nhiet deng hoc 3 Giai thich duoc co the phan tang va cac digu kien can bang hod hoc dUa tren nhang nguyen ly, dinh luat co ban, tit van dung de giai guy& nhang van de thUc te 4 Trinh bay duoc mei lien quan glib au tao va tinh chat dia cac nguyen to va cac hop chat vo co quan trong, theo hieu va giai thich duoc vai trO cua chung Y - Duoc hoc va dec tinh Giao trinh chia lam tap: Tap CAU TAO CHAT VA NHIET DONG HOA HOC gem clutong: Nhfing khai niem va Dinh luat co ban hod hoc/Cau tao nguyen tip va He thong tun hoan cac nguyen te/Lien ket va cau tao phan tit/Phut chat/Cau tao vat the — Phan civic ion/Nhiet deng hoa hoc Tap nham gitip sinh vien thvc hien muc tieu va muc tieu (6) Tlap C1-6m phan: Ph'An I CO CHE PHAN (ING VA CAC TRANG THAI CAN BANG g6m chuong: T6c va cci the phan iing — Can bang hod hoc/Si hinh va cac tinh chat cila dung dich/Dung dich chat dien ly/Phan 1.tng oxy hod khii va dOng dien PhAn II HOA HOC VO CO gem 10 chtiong, trinh bay moi lien quan gifiia cau tao va di-1h chat cac nguyen to va cac hop chat vo co; vai tro va doc tinh cila cluing sinh quyen va nhung ling dung Y-Dtioc Tap nham ginp sinh vien thuc hien muc tieu va muc tieu CuOi Tap c6 kern theo cac phu luc de nguai doc tien tra ciiu nhieu hang s6, dai hiong hoac khdi niem thttong clang Hod hoc Trong qua trinh eu k soan, van Chung t6i rat mong nhan duoc Sr kien dong gop va phe binh cUa cac do'ng nghiep, sinh vien va ban doc de lan xuat ban sau tai lieu c6 chat liking cao hon Ha NIji, Thang nam 2008 Chez bier' (7) MUC LUC PHAN I CO CHE PHAN LING VA CAC TRANG THAI CAN BANG Chtecing 7 TO'c dO va cd chg phan ling Can bAng hoa hoc 11 Le Thetnh Phu'dc - Le Kie'u Nhi 1 T6c va co chO phan Ting 12 1.1 Dinh nghia va }Dieu din to-c phan fing 12 1.2 Anh huang dia n6ng den t6c phan iing 15 1.3 Anh Iniang cua thoi gian den nOng de chat phan ling PlutOng trinh t6c tich phan 19 1.4 Anh huang cUa nhiet den -LOC phan ling 27 1.5 Giai thich cac anh Intang cUa neing va nhiet di) den to-c phan ling 29 1.6 Co the phan ling 34 1.7 Chat xtic tic tit& day to-c di) phan iing 38 2 Can bang hod hoc 42 2.1 Dai Wong 42 2.2 Phuong trinh ding nhiet Van't Hoff Hang s6 can bang 43 2.3 Hang s6 can bang K va bieu thfic tic dung kho-i Wong Q 47 2.4 Chieu hudng va gidi han cua phan iing 48 2.5 Cac dang cua bieu thlic tic dung khOi luong va hang so- can bang 53 2.6 Giai guy& nhiing van de Binh Wong lien quan den trang thai can bang 55 2.7 Su dich chuyen can bang Nguyen 1ST Le Chatelier 62 2.8 Can bang chuyen hod t6 bao 67 (8) Chito'ng Sy' hinh va cac tinh chat ciia dung dich 70 Le Thanh Phu'ac - Hoeing Thi Tuyet Nhung 1 Nhfing van de chung ve ski hinh dung dich 70 1.1 Dinh nghia - Phan loai 70 1.2 Cac cach bigu thi n6ng.d6 • 72 1.3 Can bang pha 77 1.4 DO tan - Nhcing yeu to anh hang den dO tan dia cac chat 91 Cac tinh chat dia dung dich chfia chat tan khong din ly va khOng bay hcii 106 2.1 Do ap suat hcii cua dung dich DinhluSt Raoult 106 2.2 DO tang nhiOt dO soi dia dung dich Dinh lust Raoult 108 2.3 DO nhiOt dO dung dac dia dung dich Dinh lust Raoult 110 2.4 Ap su'at tham than Dinh it* Van't Hoff 113 3 Tinh chat caa dung dich cac chat din ly 119, Chafing Dung dich chgt dien ly 123 Le Thanh Phu'dc 1 Trang thai cila chat din ly dung dich 123 1.1 Dinh nghia - Phan loai chat din ly 123 1.2 DO diOn ly (a) 124 1.3 Hang so diOn ly (K) cua chat din ly yeu Dinh lust pha loang cua Ostwald 130 1.4 Hoat dO va hO s6 hoat dO 132 2 Thuye't acid — base 140 2.1 Thuye't Arrhenius (thuye't din ly H+, OH-) 140 2.2 Thuyk Bronsted - Lowry (thuyel proton) 141 2.3 Thuye't Lewis (thuy6t electron) 144 3 S4 din ly Thang pH dia Sorensen 146 3.1 Ski din ly caa ntioc 146 (9) 4 Can bang acid — base 150 4.1 Su dien ly cua cac acid yeti 150 4.2 Su dien ly dia cac base yeu 151 4.3 Quan he gifia Ka va Kb clia mot cap acid - base lien hop 153 4.4 Su dien ly dia acid, base cia chiic Chat luring tinh 153 4.5 Cach tinh pH mot s6 dung dich 157 5: Dung dich dem Chat chi thi pH 165 5.1 Dung dich dem 165 5.2 Chat chi thi acid — base 175 6 Can bang dung dich dia chat dien ly it tan Tich so- tan 178 7 Phan ling dung dich dien ly 187 Chuang 10 Phan ifng oxy hoa khif va clong dien 191 Le Themh Phu 'dc 1 Phan iing oxy hoa khii Khai quat ve pin dien h6a 191 1.1 Khai niem chung 191 1.2 So- oxy hoa (S.0) 193 1.3 Can bang phan ling oxy hoa khii 194 1.4 Khai quat ve pin dien hoa 198 2 Pin Galvanic 199 2.1 Cau tao, hoat dOng va so d6 pin Galvanic 199 2.2 Dien the: san pha:m ciia pin Galvanic 202 3 Nang luong tu Gibbs va cong dien 211 3.1 Dien the pin chuan va hang so- can bang 211 3.2 Anh huang cua n6ng d6 den dien the dia pin Phtiong trinh Nernst 214 3.3 Dien the cilia pin va moi quan he gifia Q va K 219 3.4 Pin n6ng d6 va n6ng d6 220 4 Pin Galvanic va van dung thiic t6 223 4.1 Acquy 223 (10) 5 Pin dien phan: sit dung nang Wong dien de di6u khie'n phan ling khong tit phat 228 5.1 Nguyen 157 va hoat dOng cUa met pin dien phan 228 5.2 Xdc dinh sari phdm cua phan itng dien phan 229 5.3 Quan he dinh Wong gifia dien tich va san phdm Dinh ludt Faraday 232 6 Nang Wong hoa sinh 234 PHAN II HOA HOC VO CO Le Thanh Phu'ac Chuo'ng 11 Phan loai va tinh chgt chung cim cac nguyen to 237 Phan loai cac nguyen to theo cau hinh electron d trang thdi co ban 237 2 Tinh chat chung cua cac nguyen to nhom chinh (A) 243 3 Tinh chat chung cua cac nguyen t6chuyn tie-p (B) 244 Chuang 12 Hydrogen 255 1 Dac tinh nguyen tit va vat is 255 2 'Firth chat hod hoc 255 3 Ling dung 257 Chu'o'ng 13 Nguyen to nhom I 258 1 Nhom IA (kim loai ki6m): Li - Na - K - Rb - Cs — Fr 258 2 Nhom IB: Cu - Ag — Au 265 Chuang 14 Nguyen to nhom II 273 1 Nhom IIA (kim loai kim th6): Be - Mg - Ca - Sr - Ba — Ra 273 2 Nhom IIB: Zn - Cd — Hg 280 Chuo'ng 15 Nguyen to nh6m III 289 1 Nhom IIIA: B - Al - Ga - In — Tl 289 2 Nhom IIIB (cac nguyen to d): Sc - Y - La — Ac 297 3 Nhom IIIB (cac nguyen to 0: lanthanid va actinid 299 (11) Chu'cing 16 Nguyen to nhom IV 300 1 Nhom IVA: C - Si - Ge - Sn — Pb 300 2 Nhom IVB: Ti - Zr — Hf 322 Chu'cing 17 Nguyen to nhom V 325 1 Nhom VA: N - P - As - Sb - Bi 325 2 Nhom VB: V - Nb - Ta 345 Chu'cing 18 Nguyen to nhom VI 347 1 Nhom VI A: - S - Se - Te - Po 347 2 Nhom VIB: Cr - Mo - W 373 Chu'o'ng 19 Nguyen to nh6m VII 380 1 Nhom VIIA (cac halogen): F - Cl - Br - I — At 380 2 Nhom VIIB: Mn - Tc - Re 395 Chu'cing 20 Nguyen to nhom VIII 400 1 Nhom VIVA (cac hi6m): He - Ne - Ar - Kr - Xe - Rn 400 2 Nhom VIIIB: Fe - Co - Ni / Ru - Rh - Pd / Os - Ir — Pt 403 Teti lieu tharn kheto 421 (12) PHAN I CO CHE PHAN AG VA CAC TRANG THAI CAN BANG Chtfdng ToC DO VA CO CHE PHAN (MG CAN BANG HOA HOC M V C TJ U 1 Trinh bay each xac dinh cac phan phuting trinh to'c dd 2 Viet phodng trinh tdc otc5 vi phan vet tich phdn cho cac phcin Ong bdc 0, 1, 2, va gidi etude mot selbai town tie thu'c te: 3 Gidi thich cinh hu'dng awl nang dd, nhiet dd va yeit to khong gian can toe phdn Ong 4 Trinh bay ddc diem caa chat xac teic vet nhieng diem cktc Net czia xi c bac enzym 5 Xac dinh duvc ch,ieu hu'dng va gidi han cda mot phdn zing qua cac gici tri cda Q, K vet dG Gidi quyet etude mot so-be:a town dat tic thOc te: 6 Trinh bay nguyenlY Le Chatelier va each van dung chuyen dick can bang Phan -tang hod hoc la nhiing qua trinh dOng hoc, vat chat va nang Wong lien tuc hien dOi Bleu dien cac phan iing &lair clang phtiong trinh hod hoc la rat thuan tien va la tong cu de tinh toan Wong san phdm tao tii m0 Wong chat ban dau (chat phan ling) da biet Tuy nhien, phtiong trinh hod hoc khong cho to biet ba thong tin quan cUa mot phan ling hod hoc: Tai thai diem bat dau, phan iing co kha nang xay tai phat hay khong? No giai phong nang Wong hay can cung cap nang Wong? Tai mot thai diem, phan iing xay nhanh hay cham? Theo co the nil-Li the nao? (13) Nhung not dung cila chtiong se cho phep xac dinh hai thong tin tiep theo 1 ToC DO VA CO CHg PHAN fiNG 1.1 Dinh nghia va bieu din Vic phan ling • Tdc dO phdn zing la sti bien doi niing cua chat dciu hay san phei'm mot don vi thdi gian: + C2 - C I + AC t - t — At (7-1) day, V IA tec dO trung binh khoang thai gian tit t1 den t2; AC IA su bien doi n6ng dO mol/L cna chat dau hay san phAm tit C1 den C2; vi tO-c dO IA dai lacing khong có gia tri am, nen dau + itng v6i viec xac dinh t6c theo sit Eden d6i n6ng san phAm, dau - itng voi chat dau Khi At —> 0, phtiong trinh (7-1) cho t6c dO titc thai: V = +dc dt Doi voi mot phan ling bat kST, chang han: aA + bB —> eE + fF trong a, b, e, f IA cac he s6 tST Wong phuong trinh hoa hoc, thi tec dO phan ling dttoc xac dinh bang he thfic: V dc A dC B dc E dc F (7-3) adt bdt edt fdt Chu 51: Don vi thai gian tee dO phan ling the IA giay (s), phut (min), gia (h), (d) hoac thong, nAm Theo do, t6c dO co this nguyen IA mol/Lgiay (hoac mol.L-1.s4); mol/Lphnt (hoac Gia tri cua V phu thuOc vao viec quy ve chat nao (trong pinking trinh hod hoc) de tinh: chat có he s6 ty Wong Ion, gia tri bang s6 cila V cang 16n • Vi du ve' ccich xac dinh tdc de): phcin zing theo thai gian Xet phdn zing thuCin nghich d pha gia'a ethylen va ozon (kw khoi quang hoci, gay o nhijm tit giao thong a pho): C2H4 (k) + 03 (k) C2H4O (k) + 02 (k) Tit he s6 tY' Wong cho thay n6ng caa hai chat dau giam xueing voi t6c dO nhu nhau: (14) V = A[C2H ] A[03 ] At At Bang cach theo doi nemg d6 dia mot hai chat dau, to c6 the tinh dtfOc t6c d6 phan itng Gia sit da bi'et ang d6 03 melt binh kin 30°C (303K) tai cac thai diem khac phut dau tien sau C2H4 dtioc dtta vao binh (bang 7.1) Bang 7.1 N6ng d6 03 cac thOi diem khac phgn Ong vdi C2H4 303K Thesi gian (s) N6ng d6 03 (mol/L) 0,0 3,20.10-5 10,0 2,42.105 20,0 1,95.10-5 30,0 1,63.10" 40,0 1,40.10' 50,0 1,23.10-5 60,0 1,10.10' + Tinh to/c d6 trung binh cua phan iing 60s: V60 = (1,10.10-5 mol/L) - (3,2.10-5 mol/L) = 3,50.10-7 mol/L.s 60,0 s - 0,0 s + Tinh t6c d6 trung binh cUa phan ung 10s dau tien: (2,42.10-5 mol/L) - (3,20.10-5 mol/L) VIO(t16u) - 7,8.10-7 mol/L.s 10,0s-0,0s + Tinh t6c trung binh cua phan itng lOs cu6i cila phut dau tien: v.10(cum = (1,10.10-5 mol/L) - (1,23.10-5 mol/L) \= 1,3.10-7 mol/L.s 60,0 s -50,0 s Tit cac ke't qua tinh tren day cho thay: ban than t6c d8 phan ling luon bi:en doi theo thai gian; t6c chain dan qua trinh phan fing (t6c di) lOs dau nhanh gap tan lOs cu6i); t6c d6 trung binh mot khoang thai gian khong cho bie't t6c tai mot thai diem Neu chon khoang thai gian cang ngan, gia tri t6c d6 thu duoc cang gan t6c d6 tiic thai (15) 40 2(1 3(1 Thai gian (s) flung V (mol/L.$) a 10,0 x 10-7 b 3,50 x 10-7 7,80 x 10-7 d 2,50 x 10-7 e 1,30 x 10-7 duang cong tai thai diem t = 35s 4j0 J N6ng dO 03 (mol/L x 105) 3,0 2.0 1,0 10 50 1 60 udi du'eing cong tai mot thdi diem cu the' cho bi'dt tdc dO tic thol tai thOi diem Vi du tren hinh 7.1, to/c dO phan -ling giay this 35 sau phan Ung bait dau la 2,50.10' mol/L.s, la dO d6c cUa tiep tuyen \Ted Hinh 7.1 Do thi Wong c16 03 theo thai gian phan ling vOi C2H4 (ye theo so lieu cOa bang 7.1 va cac ket qua tinh tOc cho vi du clang xet) DO dific cOa duting thang b la to'c dO trung binh di' a phan ling ci cä 60s, cOa duttng thAng c va e le tek trung binh lOs dgu va 10s cu6i; dO dek cOa a la t6c c10 ban au tai thai diem t = 0,0s, cOa d la tcic chi ttic thai tai thOi diem t = 35s • Nhi:ing hiu y can dung cho phAn trinh bay tiep sau: Thuat ngia "t6c dO phan ling" thong thttang la de chi t6c dO tfic thai T6c dO ban dau la t6c dO tic thai tai thai diem cac chat dau moi trOn fan vdi (nghia la t = 0) Khi do, n6ng dO san pham la rat nhO nen teic phan ling nghich khong clang ke Trii nhiing truang hop dac biet, to se sit dung t6c dO ban dau de xac Binh cac thong s6 Ong hoc khac cua phan T6c dO phan itng phu thuOc trtioc het vao ban chat ciia cac chat tham gia phan itng, this den la n6ng do, trang thai vat ly cua chung, nhiet ma (16) 1.2 Anh htaing clad nang clgn tac phan iing • Phticing trinh to-c di) hay dinh luty tij-c d() (con goi la dinh ludt tac dung khai Wong, Cato Guldberg va Peter Waage, hai nha hod hoc Na Uy, dua dang thiic ban ddu nam 1864): • Tdc dO phdn zing le thuein voi, tich so nesing dO (vdi so ma thich hop) cda cac chlit tham gia phdn zing vdi mat phan iing chung, chang han: aA + bB —> san phdm Phuong trinh tac c6 V = k.[A]m.[B]" (7-4) [A], [B] - n6ng mol/L cua chdt A va B thOi digm tinh V m, n - nhUng so/ duct xac dinh bang thiic nghi0m; tang m + n &toe goi la bac cua phdn zing, m la bek rieng ctdi vdi A va n la bac rieng ctoi vdi B Cac s6 mu khong nhdt thigt phai c6 bdt ky mai quan 110 nab vdi cac 110 s6 a, b phtiong trinh phan k - he so q, 10, goi la hang so- tot do, chi phu thuac vao ban chdt cUa chd.t phan iing va nhigt voi mat phan -tang xac dinh va nhigt ct6 khong doi thi k = const Khi n6ng d6 cac chdt phan iing dgu bang mol/L, k = V va goi tdc dO rieng cda phdn Phuong trinh (7-4) cluoc goi la dinh ludt tac do, phuong trinh tac hay pinking trinh clang hoc hinh thiic cua phan ling; no phuong trinh co ban cUa dang hod hoc va &foe xac dinh bang thiic nghi.0m • tim chtoc cac phdn cua dinh ludt tot (g6m tac do, bdc phan ling va hang so/ tac do), ngtiOi ta phai thiic hiOn nhigu thi nghi0m cac n6ng ban cldu khac de xac dinh mat boat gia tri van tac ban ddu Mat cla" bigt phuong trinh tac clod nhik nao d6, ta c6 thg dung no de xac dinh tac bdt ky n6ng chdt ban cidu nao Chu 51: DOi, v6iphan ling clang thg, la phan gicia cac chdt tong pha (chang han phan iing giita cac chdt khi, giita cac chdt hoa tan dung dich), n6ng cac chdt phan *rig (Moe th0 hi0n ddy du pinking trinh tac (17) S (r) + 02 (k) -> SO2 (k) V = k'.const.[02] = k.[02], • Xac dinh bac phan ling a/ Bac chung ciia phan ling, hay bac rieng doi vdi ding chat, thltang la s6 nguyen &tong hay 0, nhttng cling c6 the la phan s6 hoac am Dieu ctuOc thay o cac vi du sau - Phan ling: NO (k) + 03 (k) -> NO2 (k) + 0, (k) Phuong trinh to/c (da duoc xac dinh qua thtic nghi:On) IA: V = k.[N0].[03] Vay, phan ling la bac dal voi NO (t6c phan iing phu thuac n8ng NO tang theo bac [NO]') N6 cling la bac doi voli 03, la [03] Tang cac bac rieng se la bac cila toan bo phan ling Vay phan ling la bac - Phan ling: 2NO2 (k) + F2 (k) -> 2NO2F (k) Pinking trinh t6c duoc xac dinh: V k.[NO2].[F2] Vay, phan ling la bac doi vdi NO2, bac dal vdi F2 va toan ba phan ling la bac Phan fing gifia chat long: (CH3)3CBr (1) + H2O (1) > (CH3)3COH (1) + HBr (aq) Phtiong trinh t6c do: V = k.[(CH3)3CBr] Phan ling la bac d6i v6i 2-bromo-2-methylpropan Pang chn Sr la riling do rat6c khong xuat hien phuong trinh toc Phan ling la bac doi vdi Hz0 ([H90]°) Di6u co nghia la t6c phan ling khong phu thuac vao ang H2O (vi no la dung moi neing 16n c6 the xem la khong d6i) Ta cling c6 the viet pinking trinh t6c do: V = k.[(CH3)3CBr].[H20]°, va bac clia toan ba phan ling la bac - Phan fing phan huS, chat khi: CH3CHO (k) -> CH4 (k) + CO (k) Phuong trinh Vic do: V = k.[CH3CH0r2 (18) - Phan Ung phan huY' ozon: 03 (k) Phuong trinh t6c d6: 3 02 (k) V = k.[03]2.[02] = k.[03]21[02] Vay, n'eu n6ng d6 02 tang len gap doi thi t6c d6 phan giam xu6ng mot niia Bac cua phan chung la bac b/ De xac dinh bac phan itng, nguai ta tie'n hanh nhieu thi nghiem M6i thi nghiem bat dau ang d6 khac d6i vdi chat khao sat, nOng d6 cac chat khac &Joe git nguyen Tii m6i thi nghiem se tim thay mot to-c d6 ban dau So sanh cac gia tri t6c d6, ta tim dude bac phan Vi du: De xac dinh bac ciia phan NO2 (k) + CO (k) —> NO (k) + CO2 (k) mau nau khong mau khong mau khong mau nguai ta tien hanh cac thi nghiem mau binh mau (da bie-t the tich) dm may quang phO Vi chi NO2 có mau (do hap thu anh sang nhin thay mot khoang bulk song hep) nen t6c d6 giam ang d6 dia no duck mau theo thcii gian Cac du lieu thuc nghiem thu &foe ghi bang 7.2 Bang 7.2 Cac t6c d6 ban dau va n6ng d6 ban dgu thi nghiOm cOa phgn Ong gii7a NO2 va CO 25°C Thi nghiem T6c ban au (mol/L.$) [NO2] ban crau (mol/L) [CO] ban dau (mol/L) 1 0,0050 0,10 0,10 2 0,0800 0,40 0,10 3 0,0050 0,10 0,20 Pinking trinh t6c d6 cho phan tang dang khao sat &toe viet &ten clang tong quat la: V = k.[NO2] m.[CO]" De xac dinh m va n, ta lap ty s6 gii a cac plitiong trinh t6c d6 d cac thi nghiem, chn y gian uOc k (do ding nhiet d6, gia tri cila no khong doi.) va gian cac nong d6 giong nhau: V2 = k [NO2 ]2n [CO]2 k.[NO2 r r 7■TC) 12 J \m [Na]i (19) (chn nhang s6 ghi phia duoi V va [ ] la s6 this tti dm till nghi:e.m) Tif tim thay m = 2, phan -ling la bac deci vdi NO2 V3 =, k.[NO2 ]i.[C0]`31 _ ([C0]3 V1 k.[1\102 ] [C0]111 [C0]1 0,0050 mol/L.s (0,20 mol/L)n 0,0050 mol/L.s 0,10 mol/L Tit tim thay n = 0, phan Ting la bac cloi vdi CO Phuong trinh toc cua phan Ting duoc xac dinh qua thuc nghi'm la: V = k.[NO2]2.[C0]° = k.[NO2]2 Vay phan ling chung clang xet la phan -ling bac • Xac dinh hAng so t6c Khi da bie't cac gia tri t6c tai mot nhiet c16, ang c16 chat phan ling va bac phan ta de dang tim duoc gia tri cila hang s6 t6c k D4 vi du, ta tra lai phan ling gilla NO2 va CO vita xet tren, thi gia tri k co the chide tim thay, chung han tit thi nghi.01 3, bang each lap he thfic sau: k = V3 0,0050 mol/L.s \= 0,50 L.mol-1 s-1 [NO2 ]i (0,10 mol/L)2 Di nhien d ca lan thi nghi4m (tai 25°C), k cua phan -ling clang xet phai có cimg gia tri (frit nhung sai s6 th-qc nghi.rn cho phep ttiOng -ling vdi chinh xac cua phuong phap cluoc sU dung) Bang each b6 tri thi nghi:On va cach tinh tttdng tit nhtt vay, chting ta có the tim cluoc gia tri k cho moi phan ling có cac bac khac Chti ST rang, this nguyen (don vi) cila hang s6 t6c di) phu thu(ic vao bac cua phan ling (bang 7.3) Bang 7.3 Cac don vi coa hang s6 to‘c k cho cac bac phan khac Bac phin ang Don vi cita k (thoi gian t theo gray = s) 0 mol/L.s (hoac mol.L-1.s-1) 1 1/s (hoac s-1 ) (20) / Cong thfic chung cho n6ng dQ mol.L-1: don vi k — rno/r4c-I t hoac cho ang dQ khdi quat: don vi cila k = (don vi ang 4)1-B4c x (don vi thai gian)-1 1.3 Anh Inking cita- thdi gian den niing d'(;) chat phan itng Phtidng trinh to-c tich phan Cdc phtiong trinh t6c viia xet tren day chata bao g6m thai gian dttoi Bang Wen thien Chung chi cho ta biet t6c d0 hay n6ng tai mot thai diem tra lai cdc cau hOi: sau bao lau thi mot chat phan ling het, hoac nan.g dQ cua no- bang may sau mot khoang thai gian nao do, ngtiai ta Can phai xay thing cdc pinking trinh mo to moi quan he dinh Wong gifia n8ng d6 va thai gian cho cac phan -tang a cdc bac khac Nhcing phtiong trinh nhu vay dUoc goi la cdc phtiong trinh dOng hoc hay phu'ang trinh tde ctO tich phan cua cdc phan iing hod hoc Chung do'ng thai la cong cu ginp cho viec tha'm dinh va xdc dinh cdc thong s6 diing hoc khdc (bac phan ling, hang s6 t6c do, chu kST ban huY ) 1/ Phdn ang bdc khong la phan fing ma t6c di) cila no la mot hang s6, khong phu thuQc vao n6ng cua cdc chat phan ling va thai gian Cdc phan ling A —> san pharn la bac khong thi pinking trinh t6c dQ vi phan cho chat phan -Cing A nhtt sau: - d[A] V = = k o d[A] = - ko.dt (7-5) dt Lay tich phan phtiong trinh tren khoang tii n6ng d6 ban d'au [No t = den nang dQ [A] thai di6'm t, thu dtioc pinking trinh t6c tich phan: [A] fd[A] = - ko fdt [A] - [A]0 = - ko t [A]„ [A] = [A]) - kot (7-6) Thai gian ban hug, hay chu k5' ban hug, ky hie:u t112, thai gian can thiet cue' mot idea chat ban ctdu bien sdn phcim [A]o 2k Khi phtiong trinh duang thang (7-6) duoc bieu din tren thi nang - thai gian thi he so- goc cua &tang thang tga = -k0 (7-8) (21) [A], DO d6c = -k„ Hirai 7.2 D6 UV phtiong trinh t6c dO tich phan cad phdn sing bdc khOng - Vi du: 'roc dO phai mau cua mot ch6 pham giau nhorn phosphat (dtioc qua sti giam dO hap thu quang A tai = 500nm) tuan theo t6c dO bac khong voi k0 = 0,00082 dO hap thu/gia d 60°C Vay, sau bao lau mau cua the pham phai di mot niia, neu mau hien tai cita no thicic la A0 = 0,470 dO hap thu Gidi Xem A0 = [A]o va van dung pinking trinh (7-7), thu &toe: A„ = 0,470 dO hap thu t 1/2 = 2k x (8,2.10-4 dO hap thn/giii) = 2,9.102 gia 12 ngay) 21 Phdn ang btic 1: Cac phan ling A > sail phalli la bac thi pluicing trinh to'c dO vi phan có dang: - d[A] V k[A] phan: hoac lg[A] t = d[A] k.dt (7-9) (7-10) (7-11) (7-12) dt = suy phthing trinh to-c dO tich In ['Al° = kt [Al = - ig [A]o kt [A] va cac pinking trinh he qua: 1n[A] = ln[A]0 - kt hoac 1 In [A]0 t = [A] 2,303 lg[A]0 kt \= 2,303 2,303 lg [A]0 ho4c k [A] k [A] (22) t1/2 = I —In [A] I 0 = 1n2 = 0,693 k k k [At) (7-13) a day can lu'u - Chu kST ban huSi cila chat a phan fing bac (tai nhiet nhat dinh) mot hang s6khong phu thuOc vao n6ng d6 ban Tau - Neu bi4u thi plation.g trinh (7-11) theo y = ln[A] va x = t: 1n[A] = -kt In[A]o y = mx + b to thu dti6c pinking trinh &tang thang ma he so goc (dO d6c) cila no bang m = -k = tga va eat true y tai b = ln[A]o t = (hinh 7.3) Neil ye d6 thi ln[chat phan ling] theo, thai gian ma thu &toe mot duang thang di xu6ng thi la clang phan ling bac doi v6i chat phan deing thii tim du6c hang so t6c ln[A] k nh6 xac dinh dO d6c C6n ne/u ye d6 thi [chat phan ling] theo thai gian ma thu dtf6c mot du6ng thang di xu6ng thi la phan Ung bac khong doi vdi chat phan iing, d6ng thoi tim du 6c k0 qua dO d6c cua duang thang - Phan Ung bac thu6ng gap la nhang phan Ung phan huST chgt hay chat 16ng, phan ng thuS, phan, phan ng phan phong xa nhu mot s6 vi du sau + Vi du 1: 2N205 (k) -> 2N204 (k) + 02 (k) co phudng trinh t6c &toe xac dinh: V = k.[N205], vdi k = 0,0168 s 40°C Tinh s6 mol N205 lai sau philt phan iing, ngu ban dau có 2,5mol N205 chila binh th4 tich 5L va nhiet dO dude tri c3 40°C I [Al, DO clCic = -k t Hinh 7.3 D6 thi phttong trinh to.c tich phan b0c Ngu chat phan ling the thi cac phucing trinh t6c tich phan co th4 thay the n6ng dO mol/L bang n'Ong dO phan mol (N) hoac bang dp suat (P), vi chting la nhiing dai luring q, le vOi Chang han pinking trinh (7-10) ay có (23) Gidi Pinking trinh t6c d6 va thin vi cUa k cho thgy day la phan tang bac 2,5 mol N6ng d6 ban dau cUa N205 là: [N,05}0 = L = 0,500 M Van dung phuong trinh (7-11): ln[N205] = ln[N201 - kt = in 0,500 - 0,0168 s-1 x 60 s = -1,701 • = [N205] = 0,182 M S6 mol N205 lai binh 5L sau phut la: 5 x 0,182 mol \= 0,910 mol L + Vi du 2: Su phan huY hydrogen peroxyd: 2H202 (1) -> 2H20 (1) + 02 (k) duoc xac dinh la phan ling bac Trong thi nghi6m c6 xac tac d nhi6t d6 phOng, nguai to theo doi ski phan huY' H202 bang cach th6 tich 02 giai phong nh6 mot buret va nhan thy sau 65 phut niing H202 (bi6u thi bang s6 th6 tich 02 cho mot th6 tich H202 16n.g O buret doc don vi th4 tich theo mL) 9,6, rndi bat d'Au 57,90
Gidi
k = 2,303 1g (H202)0 = 2,3031g 57'90 = 0,0277 phut- t (H202 ) 65 9,60
0,693 0,693 t I = = 25 phut 0,0277 philt-1 c) N6ng d6 H202 lai sau 15 philt: 2,3031g 57,90 0,0277 = (H202 ) = 38,22 15 (H202 ) (24) + Vi du 3: Carbon 14 phan phong xa p (beta) theo phan 6 14/1/4T7' e ((3- ) có chu kST ban la 5730 nam Tinh tu6i cua mot m'Au go khao c6 có phong xa bang 71% d6 phong xa cua mdu g6 hien tai? Gicii Dtia cac dfi lieu \Tao phuong trinh (7-13) va (7-12), thu duoc: 0,693 5730 nam = k = 1,21.10-4 nam-1 k 2,303 100 t = lg = 2831 nam 1,21.10-4 nam-1 71 + Vi du 4: M6t ddn thu6c chlia aspirin (= Asp) clang lOng Can &lac pha chg cho digu tri Odin dau, sift va thong ke't tap ti.4u cdu N6 chila 325mg (Asp)/5 mL hay 6,5g (Asp)/100 mL DO tan ciia Asp a 25°C la 0,33g/100 mL Mid vay dang thu6c la hon dich (tieu phan chat tan dtioi dang cac hat treo 10 lung va gidi phong ddn Asp vao dung dich) Biel hang s6 t6c phan 1n6'7 Asp dung dich la bac va bang s-I
Gidi
— d[Asp] \= k.[Asp] dt ,Vi [Asp] la khong d6i va bang tan cUa Asp chling nao hem dich On tai thai gian to/c phan huY) Asp la bac khong bieu kien (khi h6n dich tan het no se tr6 ve Sc 1), nen: — d[Asp] k.[Asp] = k o dt k,, = (4,5.10-6 s ) x (0,33g/100 mL) = 1,5.10 gs-1 100mL (25) t = 0,10 [Aspjo = (0,10)(6,5g/100 mL) , = 4,3.105s = k0 1,5.10-6 g/100 3/ Phdn zing bac Phan Ting A + B —> san pha'm la bac thi plationg trinh to-c vi phan có dang: - d[A] - [B] V = d d \= k[A][B] (7-15) t dt Goi a va b la n6ng dQ ban dau cilia A va B, va x la n8ng dQ da phan ling den thai di4m t, thi: V = —dx = k(a - x)(b - x) (7-16) dt Lay tich phan pinking trinh tren, thu duQc phuong trinh t6c tich phan: ln b (a — x) kt (7-17) (a — b) a (b - x) Khi A va B có cimg n6ng dQ (a = b), hoac coi phan ling la ciia cang chat 2A —> san pham, thi: V Phuong trinh teCc 1 ( x x d 2 k \= kt (7-19) la: (7-18) (7-19) (7-20) \= = (a - x) dt do tich phan cila (7-18) la: 1 \= va chu ky ban h4 t kt hoac [A] [A]0 cUa phan ling bac suy tit 1 / = ak D6 thi bi4u din phuong trinh (7-19) tticing ling vdi 1 \= kt + [A] [A]c, y = mx + b (26) Chit 1 + Khac Voi phan Ting bac 1, thai [A] gian ban huY' cUa phan ling bac phu thuQc vao ang dQ ban dau dia chat phan Dieu cho thay, thai gian niia phan Ung se ngan hdn có nhieu mol chat có mat de va cham va phan nhau MQt ming dQ ban dau cao se có mot thai gian ban huy ngan, mot nong ban dau thap se c6 mot thai gian ban h4 dai hdn Do d6c = k 1 [A]0 t Hinh 7.4 DO thi phuting trinh tek dO tich phan b0c + Vi du: Phan ling xa phOng hoa ethyl acetat 25°C la: CH3C00C21-1, + NaOH -> CH3COONa + C2H5OH Neng dQ ban dau cua CH3C00C2H5 va NaOH deu bang 0,01500 M Sau 20 phut ang dQ kiem giam mat 0,00993 M Tinh:
Cho biet phuong trinh t6c dQ V = k.[CH3C00C2H5].[Na0H] Gidi Phliong trinh t6c di) chi la phan ling bac
1 0,00993 k = = 6,531-1-nor' phtit -1 0,015 x 20 (0,01500 - 0,00993) b) Va van dung phuon.g trinh (7-20) de tim: t1/2 = = 10,21 phtit 0,015 x 6,53 Lu'u gia sii phan iing tren ma ban dau cho [NaOH] >> [CH3C00C2H5], thl sau mot thai gian [CH3C00C2H5] thay d6i dang ke so vai (27) 41 Phdn zing b(tc 3: Phan iing bac tong quat có dang A + B + C > san pham Goi a, b va c la n6ng ban dau cila A, B va C, va x la n6ng da phan ling cua chting sau thai gian t, to có phtiong trinh t6c dO vi phan: V = dx k(a - x)(b - x)(c - x) (7-21) dt - Trong trurang hop a = b = c hoac phan ling bac la cila chat, chang han 3A > sari pham, thi: dx V = dt k(a - x)3 (7-22) Phan ly bie-n s6 va lay tich phan, thu dive phuing trinh t6c tich phan la: 1 \= 2kt (7-23) (a - x)2 a' 'Cif suy chu kST ban hug: 3 t(/- 2a 21: 51 Phdn zing beic n: Dang phan ling là: A+B+C+ +K san phAm (7-24) (7-25) n (phan tir De don gian, gia sii n6ng ban dau cita cac chat bang va bang a, va x la n6ng dO da phan Ting cua thong, thi cac phaang trinh t6c vi phan va tich phan thu dive nhti sau: dx \= kn(a - x)" (7-26) (n —1) — ) Tit suy chu kST ban hug: 1 2 n-1 - t1/2(n) (n-1) k n a n-1 CS day, k„ va t1,2 („) la hang s6 to-c bac n va chu kS7 ban hug cila phan -tang bac n, vdi n dt \= k ri t (7-27) (28) 1.4 Anh htiang cita nhit coo d6n toe phan ling Nhiet dO anh hoeing den t6c dO cua da so cac phan ling bang each gia tang hang s6 Vic dO k Kinh nghiem cho thay, t6c dO phan iing thtiong tang 2-4 Lan m61 tang nhiet dO len 10K (hay 10°C) Con so-cho biet so Mn tang ciia tO'c phdn zing nhiet ctO tang them 10 c:1-0 goi he so- nhiet ciict tele ctO phcin zing va ky hieu la y Theo do, mot phan ling ding cac di6u kien khac thi: -= VT + 10 VT kT 10 k T (7-29) N6u nhiet dO T, van tic cua phan ling la V, thi nhiet T2 van tic V2 cna phan ling chicle tinh theo biL thi c kinh nghiem dia Van't Hoff: - Vz =Y 1" V/ (7-30) Vay, nhiet dO lam tang tic dO phan ling, ma thtic chat la lam tang hang so -LOC dO k theo mot ham Bieu thlic (7-30) chi gain thing khoang nhiet dO khong cao + Vi du: MOt phan ling coy = dtioc hoan sau 0°C Vay cling phan ling do, ne-u tie'n hanh 100°C thi:
Gicii
V100 = lo = 2)0 Vo Tic phan ling tang 210 lain
3 pinit 2'0 d 100°C phan ling hoan chi sau khoang phut - Phu'dng trinh Arrhenius: Tii nhung ke't qua nghien cflu chinh xac, nam 1889 nha hod hoc Thuy Dien Svante Arrhenius da tim mo'i quan he theo ham mu am gifia nhiet va hang s6 tic dO Cj clang hien dai, phlicing trinh Arrhenius dtioc V100 Vo t o t too (29) k = A e-Ea/RT 6 day, k - hang s6 t6c d6 T - nhi6t d6 tuy6t de:a R - hang s6 e - co sec logarit tv nhien A - mot hang s6 có lien quan den s4 dinh litiong st.i va cham giiia cac phan tii (Sr nghia dia no &toe thao luan a phia sau) E - na ng lu'o'ng hoat hod cad phan zing, theo Arrhenius, la ruing lacing toi thdu ma cac phcin tec' can phdi c6 cte' phan zing Cy nghia chinh xac hdn dm no, cang nhu A, se not tiep a phan sau) Khi lay R = 8,314 J/K.mol thi Ea có thin vi la J/mol Nilo rang, nhi6t d6 tang, so- mu am se nha hdn, gia tri k ft-6 len lon hdn, nghia la t6c dO tang Cluing ta có tinh ctiOc E bang cach lay In hai v6 phtiOng trinh Arrhenius va chuyen dang phtiong Ink Y trinh Ea \= ( mot &tang thing: + InA (7-32) R T i = mx + b D6 thi Ink theo 1/T cho mot &tang thing ma d6 d6c dm no la - E./R va cat y d lnA (hinh 7.5) Bang thifc nghi6m, mot s6 gia tri k a cac nhi6t d6 khac va lap d6 thi nhii hinh 7.5, vi R da biet, nen tinh &toe Ea = -R.tga Cling có the xac dinh E bang cach lay dao ham Ink theo T: cl In k Ea ( dT RT 7-33) Neu xem E = const, tich phan phitong trinh tren tilt T1 den T2, thu &foe: Ink I/T (K- ') Hinh 7.5 Xac dinh Ea b6ng thi bie'u din Ink theo 1/T (7-31) k \= _Ea r 1 Ea k l R \T2 T1) R ( 1 T1 T2 (7-34) Thilc to rat don gian, chi can xac dinh k1, k2 cua phan ling c3 hai nhiet d6 T1, T2 r6i thay vao (7-34) ta se tim diloc gia tri Ea Ngiicic lai, n6u da biet Ea Ira (30) + Vi du: Tinh Ea cua phan ling phan 2H1 (k) —> H2 (k) 12 (k) Biet k 500K la 9,51.10:9 L/mol.s va 600K la 1,10.10 ' L/mol.s Giai Ap dung phtiong trinh (7-34), to ( k Ea -R In k I \ T 1 2 T1 ( 1,10.10-5 Lb-11°1.s \( 1 \= - (8,314 J/mol.K) in 9,51.10 -9 L/mol.s 600 K 500 K 1,76.105 J/mol = 1,76.102 kJ/mol 1.5 Gfai thich cac anh hu'ang cua n6ng d6 va nhi6.t den t6c phan ling 1.5.1 Thuyet va cham hoat di:mg A - Thuyet va cham giai thich phtiong trinh t6c d6: D6 phan ling hoa hoc xay ra, cac phan tip chat tham gia phan ling (nguyen tU, phan tU, ion, g6c to do ) phai va cham vdi Nhu vay, tdc cto phdn eeng theyc quyet Binh bdi so va cham gieea cac phan to chat 1 dcm vi thol gian S6 va cham nhi6u hay it lai phu thu6c vao n6ng d6 chat lOn hay nhO It6t cu6c, t6c d6 phan ling tY 1e thuan voi n6ng nhu da thay phtiong trinh t6c d6 (7-4) Nho rang phtiong trinh ay chila tich khong phai t6ng) cac n6ng d6 Vi lai nhtt vay? Mo hinh don gian hinh 7-6 d6" dang giai thich di6u - Khong phai moi va cham gifia cac phan tip clew d'an den phan ling Thuyet va cham hoat Ong cho rang, chi flitting va cham giiia cac phan tip c6 nang Wong 4fi lon, goi la cac phan tit hoat Ong, moi c6 th6 gay phan ling Hinh 7.6 T6ng s6 va cham giUa cac tau phan Nhfing va cham nhti vay dtioc goi la va cham có th6 hi6u qua hay va cham du nang A va B /à tich (khOng phai t6ng) cac s6 lacing tido • NhiOt do$ tang có tdc dung lam tang so va chain phan A va B (tuang Ong det nang lu'o'ng, ma thu'c chat la lam tang so-phan tee v6i tich cac Wong c10 ceia hoat dOng Ca'n htu y: day la nguyen nhan chInh A va B) 4 va cham Them 6 va cham Them (31) lam cho t6c dO phan ling tang nhanh tang nhiet dO (nhui da thay d vi du phia trutoc, nhiet dO tang 100°C, t6c dO tang 210 lan), chit khong phai nhiet dO lam tang chung tang s6 va cham binh thutong (vi ne-u nhur vay, theo tinh toan Ong hoc, t6c dO phan ung chi tang khoang 1,5 Fan, khong phai 210 lan, nhiet dO tang them 100°C, vol y van bang nhut vi du da dua) - Co the tinh dtioc s6 phan tit boat &Ong hay so va cham du nang lacing theo dinh lukt phan 136 Boltzmann cho cac loaf hat Wong ttt 1ST Wang: N* -E,/RT (7-35) N N* - s6 phan tit hoat &Ong N - tang s6 phan EA - nang Wong can thiet de chuyen mol A có nang Wong trung binh tra boat &Ong va goi la nang Wong boat hoa A R - hang so" khi, bang 8,314 J/mol.K T - nhiet dO tuyet e - cd s6 logarit tLt nhien Xet phan ling: A (k) + B (k) -> san ph'am Pinking trinh t6c dO: V = k.[A].[B] (7-36) Theo thuye't va cham boat &Ong thi chi nhiing phan tit hoat Ong inch gay phan ling, do: V = 13.[A]*.[B]* (7-37) [3 - he s6 tS7) le [A]* va [B]* - ming dO cac phan tit hoat dOng A va B Theo (7-35) thi: [A]* = [A].e-EA/Fa va [B]* [B] e-E,e/RT (7-38) thay (7-38) vao (7-37), ta có: EA +E„ V = 13 [A]* [B]* = RT [A].[B] = fle-E' RT JAMB] (7-39) 6 day, Ea - nang Wong hoat hod dm phan Ting va Ea = EA + EB (7-40) Z* - s6 va cham du nang Wong Z - tang s6 va cham (32) 11/ la va cham du nang Itldng Idn han Ea k= [3.e-E" /RT =EJRT deng thai nhan tS'T le va cham du nang Wong tai met nhiet de (kST hieu f) chinh la thila so- ben phai phiiong trinh Arrhenius: Z* e-Ea /RT \= f (7-41) Thlia sof cho thay, ca Ea va T cteu anh huOng den tS, le va cham du nang lilting, tfic la Anh huOng den tec phan ling hay chinh IA lAm thay ct6i hang se t& k Khi T tang se khuech dai tY' le va cham có du nang liking vUot qua &foe hang /An nang liking hoat hoa Ea, nhu trinh bAy hinh 7.7 va bang 7.4 Bang 7.4 Anh hvang dm Ea va T der) ty le (f) va chum du nang Ivong de co the phan Ong Ea (kJ/mol) f (a T = 298K) 50 1,72.10-9 75 7,13.1014 100 2,96.10-18 T f (iii Ea = 50 kJ/mol) 25°C (298 K) 1,72.10-9 35°C (308K) 3,31.10-9 45°C (318K) 6,12.10-9 Du lieu bang 7.4 cho thay, vii Ea = 50 kJ/mol - met hang rho nang hong ph6 bien dia nhieu phan Ung, gia tri f (clang clia tec de phan ikng va hang s6 toe k) tang g'an gap doi moi nhiet tang 10 de - Cdu trait phan tee anh hu'C'ing den tdc dO Nhu da biet, so va Hinh 7.7 Anh twang cua nhiet len Sc! cham du nang Wong gifia cac phan b6 cac nang luring hoot hoa phan tii hoat thing có the dan (= nang Ivong va cham) d nhiet cid cao den phan king chi chiem ty le hon T2, t.cf 10 va cham du nang ItiOng de vVot qua Ea IOn hon (f) nhO tong so va cham Tuy nhien, ca tS'T le nhO et-mg data phan anh dung s6 Wong va cham có hieu qua ma thtic ski gay phan king Con can met yeu te; de va cham du nang liking co hieu lye phan king ski dinh hiking ching cua cac phan tii va cham Trong pinking trinh Arrhenius k = A.CEJRT, thifa s6 A ham ch-da yeti to khong gian Ngvai to goi A la thila s6 tan s6 vdi A = p.Z, Z la tan s6 va cham va p theta so (33) ve mat cau frac cua cac tie2u phan va cham, c6 the coi no nbit la ty le va cham có hie2u qud caa cac phan hoat &Ong du'qc dinh hu'ang thing Tit cac quan h8 da neu, de dang rut bi4u thitc chung cua hang so t6c d6 la sit tIch hop cita cac ye-u to va cham (Z), nang lUong (1) va khong gian (p): k = p.f.Z (7-42) Va cham gifia cac nguyen tit rieng le có p 1, vi cac nguyen tit cd ban c6 hinh cau, khong phu thuOc nhie'u vao hitong Phan ling: NO (k) + NO3 (k) -> 2NO (k) c6 p = 0,006, tiic la chi có va cham 1000 va cham nang lacing duoc dinh Intong khong gian thing de dan den phan ung Trong cac phan ling hod sinh, cac phan tit nhO can dinh Inking dung tren nhfing \Tung khong gian cuc nhO cUa cac phan tii cue kin (protein, acid nucleic vii vai tro enzym - xtic tac sinh hoc), p c6 gia tri < 10-6, tile la c6 it ban trie2u va cham vii day di' nang Wong tao ditoc san 1.5.2 Thuyet trang thcli chuyin tiep Thuye't va cham boat &Ong clan gian, de hinh dung, nhung khong not ri5 nang Wong hoat hod dUdc sit dung nhU the nao va phan tii hoat dOng bie'n doi Nhu da bik chudng (Nhiet dOng hoa hoc), not nang dm 118 la tang &Ong nang va the nang cua 118 phan di xa dang chuyen dOng lai gan vii tOc dO rat nhanh, dOng nang cita chting lin, the nang thap Khi chung tra nen sat nhau, mot phan dOng nang chuyen sang the nang, vi cac dam may electron cila chting day Tai thai diem va cham, cac phan tii ditng lai, dOng nang cua chting chuy8n th8 nang va cham Neu the nang va cham khong kin hdn hoac bang nang luting hoat hod Ea, chting bat nhu nhfing qua bong ban Ngtioc lai, the nang va cham du lin va cac phan tit lai dinh huong khong gian dung, chting se vuot qua laic day Hat nhan cua nguyen tit but electron dia nguyen tit kia, cac orbital xen phit vao va mat dO electron thay doq, vai lien kat dai va 34u di mot s6 lien ke't moi bat dau hinh thanh, phan tit chat phan ling chuyen dan sang phan tii san pham O nhfing di8m giao thai su6t qua trinh chuyen hod, ton tai khong phai chat phan iing hay san pham ma la cac tieu phan chuyen tie-p vai nhii'ng lien kat khong hoan chinh Cdc tie'u phan cuc kST khong en dinh the nang rat kin, chung chi ton tai khoanh khac h8 phan iing dat nang Wong cao nhat Ngtfoi to goi dO la nhungphitc chat hoat &Ong hay nhiing trang thcii chuyen tie-p cua phan ling, va chting chi hinh neu cac phan tit (34) Chit phin Ong Trang thai truck chuygn tiip Trang thai chuy6n tip Trang thai sau chuy6n ttep H H OH Br —CA , OH 1.` H H San phgrn Br —OH H H H Br• OH Br' OH H H H H vay, nang luring hoat hoci du'o'c clang cho viec keo dai va lam bie'n clang cac lien ket dat tdi trang thdi chuyen tie' (chung to nhAn biet &toe trang thai chuyen ti6p nhO phep phan tich quang ph6, b6i vi hdu nhu kh6ng the phan lAp dude nhang tieu phan nay) Hinh 7.8 minh hoa don gian cho cac y tren thong qua phan itng gifia methyl.bromid va ion hydroxyl: CH3Br + OH- -> CH3OH + Br- Can them luu y cho hinh 7.8, nhung clang la chung cho thifc to cac phan ling: - Viec dat tdi trang thai chuyen ti6p van khong dam ban rang phan ling se tien trien tao san phAm N6u lien k6t C-0 tie-p tuc ngan lai va ben them, san phAm dude hinh Con neu lien k6t C-Br ngan lai va ben hdn, trang thai chuyen tiep se phan huy tr6 lai cac chat ban dAu Vi th6, theo mau hinh ay, moi phdn zing de'u la thudn nghich A Br`u CH,OH Oua trinh phan ang Hinh 7.8 Sc d6 nang lacing ph5n Cmg gicla CH3Br va OH- Nguyen ter Br tich dien am nen C trong CH3Br tich dien ducng Cac tau phan ph5n sing vita ph5i chuy6nd6ng du nhanh (d6 dat Ea), vela phi Binh hu'Ong dOng d6 nguyen iii"C6(+) ti6p can duvic 060 (tich dien am) ctia OH-, tCi dO bat dau hinh lien kat C-0 d trang thai chuyen ti6p, C du'Oc bao quanh b6i nguyen tzr khac theo kau luting thap tam giac nang lu'ong cao ma kh6ng bao girl co cac hOp chat C binh thtiOng - M6t phan itng thuAn nghich c6 nang Wong hoat hoa: Ea cho phan (35) thai da duoc hoat hoa va chat san pham D-6i voi phan ging toa nhiet thi E < d6i v6i phan ling thu nhiet thi ngtioc lai, Ea > Ea' (phan the hien hinh 7.8 la phan iYng toa nhiet) N6u bi6t Ea Ira AH cUa met phan ling, ta có tinh duoc E„' cua phan ling va ngticic lai Vi du: phan 03 (k) + (k) 02 (k)
Gidi Phan ling toa nhieu nhiet nen mile nang Wong cUa san pham rat thap De san pham dat den trang thai chuyen ti6p, can cung cap cho san ph -am met nang Wong bang AH,,„ + E„, nen Ea' = + Ea = -(-392) + 19 = 411 kJ So dO nang hiring cua phan ling cc') 'clang hinh gieing nhu d hinh 7.8 1.6 Cd chg phan iffig H61.1 het cac phan ling hod hoc xay qua nhieu btioc cd ban la nhfing phan ling so cap Tap hop cac phcin zing sq cap cte' phdn zing chung duvc goi la cd the phdn zing Chang han, co ch6 cho phan iing chung 2A + 13' -> E + F co the Om buoc cc; ban la phan ling sd cap: A + B C + A D C D E + F Phan Ling tong: 2A + B E + F chinh phan (mg chung Ccic co' the phdn zing va phan tee sal Nguoi ta quy Binh: m6i buck co ban hay m6i phan ling so cap khong tao cac but& hay phan ling don gian han nfia 1V16i boric co ban duoc dac trting b6i cac phan td' so; la so cac tau phan phcin zing mji bzddc Vi du xet phan ling phan huS'T ozon d thucing tang khi quyen Phan ling chung 203 (k) -> 302 (k) (36) (1) 03 (k) 02 (k) + (k) (2) 03 (k) + (k) 202 (k) Phan ling t6ng: 03 (k) 02 (k) Cj buoc (1) chi c6 ti6u phan tham gia phan ling nen goi la phcin zing phcin td' CS buck (2) c6 tieu phan tham gia phan ling, quy uoc goi la phdn zing 2 phan td' Phdn zing phcin td' rat hi6m gap b6i xac suat de ti6u phan va cham ding hic vdi nang Wong day du va dinh hoeing khong gian dung rat be Phan ling c6 phan tii s6 cao hdn chua dtfoc bi6t Khac v6i phan ling chung, phu'o'ng trinh toe da cda phdn (Pig sd cap có the' ctu'o'c suy tit he at.); lu'o'ng ciia phdn zing, va bCic phiin (mg bang phan so: + Vi du: Ngtioi to de nghi cd ch6 buoc la phan -tang sd cap dui% day cho phan ling chung: (1) NO2C1 (k) NO, (k) + Cl (k) (2) NO2C1 (k) + Cl (k) NO, (k) + C12 (k) Cho bi6t:
Gidi
2NO2C1 (k) 2NO2 (k) + C12 (k)
Tat ca cac phan ling sd cap cd ch6 khong c6 cling t6c dO Bu'o'c cham nhdt so v6i cac bu6c khac ducic goi la buoc gioi han t6c d6 hay buoc quy6t (37) Tra lai phuong trinh gala NO2 va CO (da neu muc 1.2 (phia tren), bang 7.2), phan Ung chung là: NO2 (k) + CO (k) -> NO (k) + CO2 (k) Neu phan itng chung phan ling so cap, phuong trinh t6c dO duoc V = k.[NO2].[CO] Tuy nhien, nhii da biet, phuong trinh t6c dO thuc nghiem lai chi ra: V = k.[NO2]2 Vi the, mot co the bUdc dtioc de xuat: (1) NO2 (k) + NO2 (k) -> NO3 (k) + NO (k) [cham, quyet dinh t6c d8] (2) NO3 (k) + CO (k) -> NO2 (k) + CO2 (k) [nhanh] Phuong trinh t6c dO cho budc co ban là: (1) V1 = ki [NO2].[NO2] = k,.[NO2]2 (2) V2 = k2.[NO3].[CO] Neu k, = k thi budc (1) la look qUyet dinh t6c dO phan itng Thtic t6 da xac nhan, dung k, = k N/A phan ling so cap (1) cham den mitt có the gia thiet phan Ung chung xay theo Woe (1) va phuong trinh t6c dO kh8ng chfia [CO] ei day can chti ST: NO3 la san pham cua bulk (1) Ira chat phan ling bulk (2) NO3 &rig vai tro chat trung gian, khong xuat hien pinking trinh phan itng chung da duoc can bang, va s-ct ton tai ciia no tam thai nhung hoan toan can thik de phan iing xay Khdc voi trang thai chuyen tiep (cac plific chat boat dOng), chat trung gian la cac phan tii voi cac lien kk binh thuang va doi chting du On dinh de co lap duoc [giai Nobel Hod hoc nam 2006 dtioc trao cho Roger D Kornberg, nguai My, v8i nhcing nghien cifu ye qua trinh chep thong tin cac Bien va su truy6n thong tin de tong hop cac protein - day, st.f tim thay chat trung gian (mediator) dtioc xem IA mot phdt minh quan trong qud trinh chep] - Thiet l4p mot cd the phdn (mg Nghien cuu va de xuat co the cho phan tang phai dam bao tieu chuan: 1/ Tang tong cac phan ling so cap phai cho phan itng chung xay th-qc tIrtic te 2/ Cdc phan ling so cap phai có kha nang xay ra, nghia chi g6m phan ling phan tit hoac phan tit Phan ling phan tit duck xem IA rat it by vong xay 3/ Co the phan itng phai phis hop voi phuong trinh t6c dO (hay dinh luat t6c dO) duoc xdc dinh bang thuc nghiem (38) Ea (buoc 2) nhanh Nang Krung Trang thai chuye'n ad.!) 2NO2 + F, Chat phan irng 2NO2F NO2F + F + NO,
2NO2 (k) + F2 (k) -+ 2NO2F (k) Pinking trinh teic d6 thiic nghiem: V = k.[NO2].[F2] \fa co c14 hien dtioc chap nhan la: (1) NO2 (k) + F2 (k) -> NO2F (k) + F (k) [charn,quyet dinh t6c (2) NO2 (k) + F (k) -> NO2F (k) [nhanh] Co the phit hop vol tieu chuan thiet lap, vi: + Tang (1) + (2) cho pinking trinh phan ling chung F la chat trung gian khong xuat hien phan ling chung + Ca bride clia co the de'u la cac phan ling phan tii nen thoa man tieu chuan this + Phuong trinh t6c d6 cila phan ling cham c1 btiOc (1) V1 = ki.[NO2].[F2] Au hop vdi pinking trinh t6c d6 thtic nghiem Theo do, buck (1) la Woe guy& dinh t6c cua phan ling chung Hinh 7.9 cho thay so d6 nang ltiong cua phan ling NO2 - F2 Qua trinh phan irng Hinh 7.9 Sc d6 nang krong cho co ch6 buck caa phgn (mg NO2 - F2 M& butic co ch6 co pink ch6t hoat Ong rieng cita n6 (k)Y hi6u *) Butic (1) ch0m, giOi han t6c c16 phAn (mg Ea coa nO 16n han bu'dc (2) b/ Cd the vai bu'dc deiu nhanh Xet vi du phan ling NO - 02 Phliong trinh phan ling chung là: (39) Phtiong trinh tic thiic nghiem: V = k.[N0]2.[02], vA co ch6 &foie de xuat là: (1) NO (k) + 02 (k) NO3 (k) [nhanh, thuan nghich] -1 (2) NO3 (k) + NO (k) 2NO2 (k) [cham, quyeI dinh toc d()] Phuong trinh t6c cUa phan ling so cap bu6c duoc viet: (1) V1 (thuan) = k1 [NO].[02] va = k_1 [NO3] 6 (2) V2 = k2 [NO3] • [NO] Chit phan ling buoc (1) nhanh, cho nhieu san pham (la chat trung gian NO3) nhung lai tieu thu chAm bulk sau (nen goi phan fing "c6 chai"), vi the no phai phan ling chieu de chuyen 136-t san pham tra lai chat &Au Kiem tra co ch6 theo tieu chuan thay: + Tong (1) + (2) thing IA cho phtiong trinh phan ling chung da can bang, chat trung gian (NO3) khong xuat hien phuong trinh chung + ca bli6c la cac phan ling phan tii, nen kha thi + Plniong trinh tic ciia phan ling cham V2 = k2.[NO3].[NO] cho thay khong phn hop voi phuong trinh Vic thiic nghiem da cho Tuy nhien, vi blioc (1) thuan nghich, trang -alai can bang V1 = V., hay k1 [N0].[02] = k_1 [NO3], nen [NO3 ] = kk ' [NO][02 ] Th6 [NO3] vao i pinking trinh tic clia bueic (2), thu duoc: V2 = k2 •k [NO]2 [02 ] = k.[NO]2 [0,] Phtiong trinh t6c btioc (2) cham dd the hien phuong trinh tee thiic nghiem cua phan ling chung VAy, cd ch6 dlidc de xuat la dung Phan ling Om nhieu bti6c trung gian, hoac cling met Inc di theo ca co ch6, duoc goi nhfing phan fing.phlic tap, ph6 'Dien nhat cac phan ling n6i ti6p, song song, day chuyen, thuAn nghich 1.7 Chgt xuc tac thnc d'Ay to-c cho phan ling — Chdt xi c tac la chdt lam tang tdc clo phcin zing va chive hoan nguyen sau qua trinh phan zing Xac tac, hay sit xac tac, hien Wong thlic day tic de phan ling duesi tac (40) (Ihuo) khOng xtic tac ChSt phan (mg Ed (thuan) co xac tac H pu khOng xtic tac Ea (nghi co xuc tac duct xuc tac Ea (nghich) khOng xtic tac San pham Nang ltrong Qua trinh phan ting Hinh 7.10 So nang luang ph5n Cing cela mat qua trinh cluac xuc tac va kh6ng duac x0c tac Chat xtic tac thik ddy teic d6 phan ling bang cach chuy6nca the buac thanh co ch6 buck theo du'ang nang Itiang th6p hon TOc d6 ph5n Cing thuOn va nghich deu tang mat luting nhu nhau, nen chat )(tic tac kh6ng anh hu'ang d6n toan bij phan ung chung Ngay nay, khoang 90% qua trinh san xuat hod hoc phai sit dung chat xtic tac Hang nam, chi rieng tai Hoa Ky, hen 2,5 trieu tan chat xtic tac &toe sit dung tong nghiep Tuy nhien, thien nhien moi la "Ngtioi si dung chat xnc tac: mot to bao vi khuan den gian nhat clang dung den hang ngan chat xtic tac sinh hoc goi la enzym de tang t6c d5 cac phan ling t6 Joao can thiet cho su 1\/18i chat xtic tac có cach rieng biet de thuc hien chic nang cua minh, nlaing v6 co ban thi chat xac tac lam tang tot cho phan zing bang cach thciP nang lu'dng hoot hoci, do lam hang s6 t6c ldn hen va to-c d6 phan ling cao hen Dieu duoc the hien tren gian dO hinh 7.10 - Hai dac diem quan cila chat )(tic tac: 1/ Chat xlic tac lam tang to-c d6 ca phan iYng thu4n va nghich M6t phan ling c6 chgt xtic tac khong cho nhieu hen s6 san pham nhung no cho san pham nhanh hen nhieu Can nhan cac y nghia: (41) + Chat xiic tac khong lam thay doi trang thai can bang cua phan ling ma chi lam cho can bang dat duoc nhanh hon LST la, chat Kik tac lam tang t6c d5 mot ltidng nhu doi vdi ca phan Ting thuan va nghich, nen hang s6 can bang ciia phan ling khong thay 2/ Chat xac tac thap nang luong hoat hoa bang each tao mot cci the phan ling khac - mot &tang nang Wong m6i thap hon to goi la cci the cilia qua trinh xuc tac Gia sii mot phan ling xay theo cci ch6 bii6c vdi phan tii so- bang 2: A + B > san pham [cham], doi hOi Ea Co chat xuc tac thi phan ling chay theo cd the biidc: (1) A + xdc tac C [nhanh], doi hOi Eal (2) C + B san ph'am + )(tic tac [nhanh], doi hOi Eat Chat ink tac dttoc hoan nguyen (h5i sinh) va &tang nang Wong mdi co Ea, < Ea va Ea2 < Ea - Co loai )(tic tac la xuc tac d6ng the va xtic tac di the + Xiic tac d'Ong the: chat xuc tac ding pha vdi cac chat phan ling Noi cach khac, chat Kik tac ciing ton tai duoi dang dung dich (theo nghia r5ng, killing chi la dung dich lOng) vdi hiSn hop phan Hau het chat ink tac do'ng the la chat khi, chat 'Ong, hoac chat ran tan duoc dung dich + )(tic tac di the: chat xtic tac va cac chat phan ling i cac pha khac Xtic tac di the thuang la chat ran Wong tac vdi cac chat phan ling ii the hoac lOng Vi phan ling xay tren be mat chat ran, nen chat )(tic tac di the thuOng phai c6 vi ng be mat rat lon (gifla - 500 m2/g) de hap phu, do lam tang n6ng d5 cac chat phan ling tren be mat dO, su xiic tac lai din theo cci the chung nhu da not tren Nhieu chat ran c6 tinh hap phu manh (nhu than hoat), cac kim loai thu5c nh6m VIII B nhu Pt, Ni, Pd, Ru, Os, Ir , hay cac hop chat ciia cac kim loai chuyen tiep khac (nhu Mn02) la nhung xnc tac di the quan Xtic tac enzym (42) Enzym c6 cau trtic chigu phiic tap, khoi hieing mol thay d6i of 15000 den 1000000 g/mol Tren be mat ciia enzym c6 diem dac biet goi la vi tri hoat dQng, mot "ke niit" phan tip ma hinh the dm no dtioc quyet dinh b6i sti sap xep cac chuoi aminoacid c6 lien quan den chiic nang xuc tac dac hieu Khi cac phan tif chat phan ling (goi la co chat) va chain vdi vi tri hoat dong, phan iing hod hoc xay Vi tri hoat Ong chi la mot phan nha be ciia be mat enzym - giong nhti mot h6 nh6 dtioc dao tren stun nth, nhung c6 the chfia ca mot s6 nh6m amino acid tii nhung \Tung xa xoi cila protein Trong hau het cac tniong hop, co chat lien ket voi vi tri hoat Ong thong qua cac ltic lien ket phan tit cac lien ket hydro, lien ket Wang chic va cac llic yeu khac Enzym co cac dac tinh cua ca ).co.c tac Ong the va di the Giting )(tic tac di the, vi so voi Co chat, hau het cac enzym co kith -dui& kh6ng 16 va thilang gan voi mang to bao Tai vi tri hoat diing tren be mat enzym, phan tii chat phan ling dttoc c6 dinh tam th6i Witt la bi hap phu) de cha "doi tac" phan ling 14i se dap xu6ng gAn Gi6ng xuc tac d6ng the, vi cac nhom amino acid dia enzym toting tac v6i co chat theo ski ph6i hop da cap c6 tao cac hop chat trung gian Cac enzym la nhting chat xtic tac c6 hieu qua 14 01-Laing Chi can lay vi du v6 thug phan ure: (NH2)2C=O (aq) + 2H20 (1) + (aq) 2NH4+ (aq) + HCO3- (aq) Trong moi truang ntioc, o nhiet d6 phong, kh6ng c6 xuc tac, hang s6 t6c cua phan Ting la 3.104° s-1 (phan ling bac 1) Ciing dieu kien c6 mat enzym urease, hang s6 t6c d6 la 3.104 s-1, tang mot tram ngan tg (10 k') lan Noi chung, cac enzym lam tang tee dQ phan ling khoang 108 - 1020 gia tri ma cac rtic tac khong sinh hoc kh6ng the nao dal toi Cac enzym civic kST dac hieu, moi phan ling chi dtioc xtic tac bai enzym rieng Urease chi )(tic tac thug phan ure, khong enzym nao khac s6 vai ngan enzym t6 bao xtic tac dtioc cho phan ling Dac tinh phi thttang c6 dtioc la cau true dac hieu cua enzym, dac biet la vi tri hoat Ong Tinh dac hieu cht6c giai thich theo mo hinh "6 khoa va chia khod": khod la vi tri hoat Ong dac hieu, chia khoa la co chat Vai thap nien gan day, mo hinh - chia cling nhac dtioc thay bang m6 hinh "tay gang": tay•là co chat va gang la vi tri hoat Ong Mo hinh sau cho thay enzym c6 bien d6i cat' tnic co chat dap vao vi tri hoat dong, ski tiep )(tic gan ket tay - gang tra nen hoan hao hon (43) n6ng d6 chat trung gian (chat phan ling - xdc tac) Trong truang hop có xtic tac enzym, co chat (S) va enzym (E) tao phlic hop trung gian ES ma ang c16 cua no se quyet dinh t6c d6 tao san pham (P) Co the chung cho tat ca cac pilau ling có >clic tac enzym theo kigu "buoc dau nhanh" (nhit da trinh bay phla tren): (1) E + S ES [nhanh, thtta'n nghich] (2) ES P + E [cham, quy6t dinh t6c dO] Enzym sit dung nhigu cd ch6 de tac d6ng den lien ket gifia cac nguyen tit nham bien d6i cd chat san pham (vi du nhu lam cac lien ket ngAn lai de bgn hon; hodc dai de yeti di va dlit; be tong lien kgt co chat de tiep xtic hoan hao "tay - gang" dO phlic hop trung gian ES on dinh va thap nang Wong hoat hod; hodc cho di proton (H+) de lam tang t6c htioc guy& dinh t6c d6 phan 2 CAN BANG HOA HOC 2.1 Dal ctidng Tat ca cac phan ling co the chia tuning d6i hai loci: + Phdn ang mot chi& la phan ling tier' hanh den clung, den ma mot hodc tat ca cac chat ban dau da tac dung het de tao san pham Vi the, nguai to goi la phan ling hoan toan hodc phan itng khong thudn nghich VI du, phan Ung chdy cua propan: (k) + 502 (k) —> 3CO2 (k) + 4H20 (k) Phan ling phan hu.S'T kali permanganat nhiet d6 cao: 2KMnO4 (r) K2MnO4 (r) + MnO2 (r) + 02 (k) Ph-an Eng phan ht6'7 hydro peroxyd rihiet d6 thtthng: 2H20;-(1) 2H20 (1) + 02 (k) + Phdn ring thudn nghich la phan itng nhfing digu kien xac dinh c6 the tien •hanh dOng thai theo hai chigu ngti6c nhau, nghia cac chat dau tac dung voi cho san pham, thi ciang digu kien ay cac'ch 'at - san pham tac dung'voi de tao chat dau Vi du: N204 (k) -7= 2NO2 (k) C (r, 'long dO) + H2O CO (k) + H2 (k) H2 (k) + 12 (k) 2H1 (k) (44) - Vi phan iing hod hoc rat khdc v6 t6c do, nen cluing cling khdc ye ,d6 Hai khia canh khac MOt phan iing nhanh có the tien trien hoar' toan hay chi mot phdn v6 phia san pham ChAng han, vOi HC1 1M, hdu het tat ca cac phan to acid dien ly ion Vali CH,,COOH 1M, chi dlidi 1% so- phan to acid dien ly ion Tuy nhien, ca phan itng xay rat nhanh va hoan chi khoang dtioi gidy Thong tu, mot s6 phan itng cham cu6i ding cho mot Wong lOn san pham, nhang phan ling khdc cho rat it san pham Chang han, sau vai nam nhiet dO ph6ng, thep mot binh ,dung nu& se bi gi, nhung nueic binh khong bi phan WT Diem Wu y day la cac nguyen tac dOng hoc cua trang thai can bang dp dung cho cac khia canh khdc cua mot phan fing Tdc caa mot phan zing - la n6ng dO cua san pham tao mot don vi thai gian - chic yea phu thuOc veto su khac ve nang lifting cac chat ctdu vet trang thcii chuyen tiep Mt& caa phan a'ng - la neng cua san pham khong quan sat dtfoc sit bien doi vi mo nao nita - phu thuOc chic ye-u veto su' khcic ye nang lu'o'ng giiia chat ctdu va san phdin - Khi luring cac chat ddu mat di theo phan itng thuan bang Wong cua cluing dtioc tao tit phan ling nghich, ta not phan iing da dat toi trang thcii can bdng (TTCB) Cdc qua trinh hod hoc thuan nghich (la nhang qud trinh th-qc, khdc voi qua trinh thuan nghich nhiet dOng chi la gia dinh) bao gem: cac phan fing thuan nghich d6ng the hay di the; s-ki dien ly dia acid, base; sv thuY phan cac mu6i; sit phan ly cila phfic chat; qua trinh hoa tan; cac qua trinh chuyen pha deu thiet lap nhang TTCB Nhiem vu co ban nghien diu TTCB la xd.c dinh Oar" hi:in hop- can bang va cac yeti to anh hoeing den can bang 2.2 Phudng trinh clang nhiet Van't Hoff Hang so can bang - Tit phudng trinh [(6-69) - chtiong 6] va xet ■)i dieu kien P, T khong doi, ta có the rut tieu chudn tu' dien bien vet gidi han caa cac qua trinh hoci hoc ceing nhu' chuyen pha dG 11.tdni (7-43) pti: the hoa cila ca.'u dni: bien thien s6 mol cua caT-o tit i Wong ung he (45) Chang han, d6i vol phan ttng chung he 1ST Wang (cho gon, chi xet Om chat): aA + bB -> eE + fF (7-45) thi: AG = G1sp1 - Gicni = (euE + fuF) - (ap.A + buB) rut ra: AG = [SP] - t.t i [CD] (7-46) va d dieu kien chuan: AG" = DI;) [SP] - j4[CD] (7-47) Vay a dieu kien clang nhiet (fang ap: Neu II; [CD] > 1p.; [SP] = AG < , phan itng tu phat (tit trai sang phai) Neu Di; [CD] = µ; [SP] = AG = , phan itng d TTCB - Thay = RT1nPi [phticing trinh (6-64) vao (7-46)], thu AG = [e (t4 + RT1nPE ) + f + RT1nPF - [a (AA + RT1nPA ) + b (µCB + RT1nPB 13 ( e P t \ E F + f 14' - 1_1 (,)‘ + b ti;)3 + RT In PAa • PBb G`p GL) Da Db 1-i6k I B bd dung khoi, lu'dng (tinh theo ap sub."-t rieng phdn) hay thu'o'ng so ctia phiin Ling (q7 s6 gifia san pham chat ddu) ltic ban ddu - Gia tri bang s6 cua Qp thay doq sal qua trinh phan itng Khi he dat ten TTCB nhiet de? T), phdn cac chat khong Nen cr6i nila, Q1, = const = K1, vay: Pe AG = AG" + RT In E = AG" + RT1nQp 13: • PI13 ) bd (7-48) ei day PA, PB, PE, PF la cip suet rieng phcin ban deiu bd) cua A, B, E, F he phan fing d nhiet d6 T; a, b, e, f la he s6 hop thfic (he s6 ty Wong) PeE P t (46) Ca A 13/ CB \= Kc (RT)'" (RT)An (7-53) Kp = ( e \ PE • PF PA3 • PBb cb Kp la hang s6 can bang tinh theo dp suat rieng phan cita cac chat phan ling (7-45) clang thuan nghich d TTCB, lac t6c phan ling thuan bang t6c d6 phan ling nghich: aA CS TTCB, AG = 0, plitidng = AG° + RT1n Thay (7-51) vao (7-48) AG = RT(lnQp + bB trinh (e P E P F t + ( Q \= -RT1nKp fF (7-50) (7-51) (7-52) eE (7-48) tra thanh: AG° xep lai, to cd: = RT1n iBich va sap - lnKp) K p Chit suat rieng phan cua cac chat bieu thlic Qp, Kp dell dung don vi atm Cac phudng trinh (7-48); (7-49); (7-51) va (7-52) la nhiing clang cita phu'o'ng trinh deing nhi0 Van't Hoff - M6i lien he giaa Kp va cac hang s6 can bang Kc, K„, KN + Ap suat rieng phAn aim lY Wang lien he vdi ang d6 qua phudng trinh: Pi = n1 RT V = Ci RT ni: S6 mol chat i R = 0,0821 atm.L.mo1-1.K-1 T: Nhiet Kelvin V: The tich dm he phan fing (L) Ci: Ming cau tit i he (mol/L) Thay tong thfic cua Pi tinh o TTCB vao (7-49), thu cludc: (ce rf Kp (7-49) (47) Kc = CA, CB, CE, CF la niing An = (C;, C tF Lb 6 trang + b) ( [E]e [F]t \ (7-54a) bang (mol/L) (7-54b) /cb Ca C b \ A B d6 cac chat (e + f) - (a [A]a [B]b , thai can do la hi6u so gifia tong cac he s6 ty Wong cac chat tao va tong he s6 tST Wong the chat ban dau phan da cho Chu 51 rang, Kp chi phu thu6c nhi6t d6 (vi phu thu6c nhikt d6); va theo (7-53) thi Kc cang chi phu thu6c nhikt d6 Bi& thric (7-54a) la Dinh luat bac dung khoi luvng C Gulberg va P Waage hai nha hod hoc Na Uy thi6t lap nam 1867 nghien cifu t6c d6 cua phan 1mg thuan nghich + N6u thay Pi = n Ptow, [pInfong trinh (1-21), chiidng 1] vao (7-49) thi: n i voi K„ = 1=1 Kp = K,, e t nE•nF a nb \ n A ' B ch (7-55) (7-56) ( Prying An n' ) cb ni - so mol i TTCB En, - tong s6 mol c6 mat he phan tang can bang (k6 ca "trd" khong tham gia vao phan Pidug - ap suat tang Ong cila he hie can bang Pi - ap suat dia i hic can bang Pt.8„, va Pi clang don vi atm Theo (7-55), lc ngoai ski phu thu6c nhi6t d6 Wong tit nhtl Kp, phu thu6c vao ap suat tang va tong so mol caah6 can bang + N6u thay Pi = Ni.Pto,„g [pluiong trinh (1-22), chtiong 1] vao (7-49) to c6: / e r 0\11.1\11:3,6 ton ■• teing ) el) Kp = E F KN, (13 An (7-57) N eE N 1\l'A N bir3jth (48) Ni - n6ng dO phdn mol cita i he phan ling hic can bang, vdi NT; = ' [theo (1-21), chuong 1] Theo (7-57), KN phu thuOc nhiet dO va Pte;ng cila he can bang, nen ngu Ptis,ng (6 TTCB) = atm, thi Kp = KN Cac hang so can bang lien quan v6i nhu sau: i p All Kp = Kc.(RT)'" = Kn v, ' uing An (7-59) \ L n i Jeb = KN (13t6ng )cb Khi An = 0, nghia la so mol ye dia phuong trinh phan ling bang nhau, thi: Kp = Kc = K„ = KN (7-60) 2.3 HAng so can bang K va bieu attic tac dung khOi ltidng Q Thuong so [san pham]/[chat dau] bigu thi phan cua he phan ling thai digm xet goi la tdc dung khoi lucing (= BTTDKL) va ky hieu la Q Khi Wong chat duoc bigu din qua mot dai ltiongcu thg (Pi, C1, 1\11) thi Q duoc vigt Wong iing ChAng han vigt Q tinh theo ap slat rieng phan va tinh theo n6ng dO mol/L cho phan ling (7-45): QP = ( pe .pr E F PA pb A • bd va Qc r [E]e [F]t \ ['A]a • [Br ibd (7-61) Nhu da bi6t, trang thai can bang thi Q = K, bigu thfic Q luc goi la bigu Ur& cila hang s6 can bang (= BTHSCB) va duoc vigt cho Kp, Kc nhu (7-49), (7-54a) Vay, K la gia tri dac biet cUa Q cac s6 hang cUa san pham va chat dau dat thioc gia tri cua chting TTCB (Tif day, to chi dg cap dgn Qp, Kp va Qc, Kc la cap dai Wong thuang duoc sii dung) Hang sec can bang K chi phu thuOc vao nhiet dO va ban chat cita cac chat tham gia phan iing chic khong phu thuOc vao luong chat ban dau cita (49) rang, d TTCB, phan ling thuan nghich van din (6 mile dO vi mo phan nhung t'6c d6 dia cluing bang (6 mile dO vi mo, to khong xac dinh duoc sit thay d6i nao ve cac th6ng s6 trang thai T, P, ni ) D6 la trang thai can bang Ong 2.4 Chi6u Infeing va gi ii han cua phan iing Lam de biet mot hiSn hop bat kST cua cac chat phan ling va san phdm tai mot nhiet dO se tien trien theo hitting nao (theo chigu thudn hay chigu nghich?) de dat tdi TTCB? Co cach de dii doan: so sanh cac gia tri Q vb K hoac xet dau ciia AG - So sanh cac gici tri Q va K Nguoc voi gia tri K hang so/ in& nhiet gia tri Q bien thien, c6 the nh6 licin hay lon hdn K va he dat tdi TTCB thi bang K CO the xay truing hop so sanh Q va K 1/ Q < K thi inau s6 (chila cac s6 hang chat &du) lon hdn so vOi tit s6 (chila cac s6 hang san pham) De Q Wong &Ring voi K thi mau so phai giam va tit s6 phai tang Noi each khac, phan ling tien trien ve ben phai (chigu thudn) tao san phdm nhigu hdn cho tdi dat TTCB, d Q = K tritOng hop chigu phan ill-1g la: chat dau > san phdm 2/ Q > K thi tit s6 (san pham) se giam va mdu s6 (chat ddu) se tang cho den dat TTCB Vdy phan ling se tien trien sang trai (chigu nghich) vg phia tao chat dau day chigu phan ling la: chat dau san phdm 3/ Q = K Tinh hueng xay nOng dO (hay ap suit) eila chat dau va san phbm co cac gia tri a TTCB Vi vdy, khong c6 Men d6i thuc nao xay (3 day phan ling duoc viet: chat dau san phdm - VI du: Cho phan ling: N204 (k) 2NO2 (k) , co Kc = 0,21 6 60"C, tai mot thai diem qua trinh phan itng Ket qua phan tich cho biet: [N204] = 0,12M va [NO2] = 0,55M Vay phan Ung se tien trien theo hitting nao ve TTCB? Gidi Viet BTTDKL Qr va tinh: [NO2 ]2 = 0,55 \= 2,5 [N 04 ] 0,12 Vi Q, > Kr, phan itng chiia dat TTCB va se tien trien ve phia trai cho den Qr = Kr (50) - Xet gici tri AG Tr6 lai phuong trinh clang nhiet Van't Hoff (7-52) va viet Q, K du6i dang khai quat: AG = RT (lnQ - InK) = RT1n(Q/K) (7-62) Theo day, ta c6 the du doan chieu huong cUa phan + Neu Q/K < -> ln(Q/K) < 0: phan ling theo chieu thudn (vi AG < 0) + Neu Q/K > -> ln(Q/K) > 0: phan ling theo chieu nghich (vi AG > 0) + Neu Q/K = -> ln(Q/K) = 0: phan ling TTCB (vi AG = 0) Moi quan he theo phuong trinh (7-62) c6 nghia gi? Q dai dien cho ang d6 (hay alp suat) cua cac phdn cUa he tai bat ky thoi diem nao qua trinh phan Ting, K dai dien cho cac gia tri phan Ting dat toi TTCB Phtiong trinh (7-62) chi bien thien nang Wong tti Gibbs ciia he mot trang thai &du Q nao va nang Wong tu Gibbs dm he trang thai ket thuc K Doi vdi he TTCB, Q tra nen bang K, vi the AG = Noi each khac, a TTCB khong xay su bien &Si nang ludng, he da giai ph6ng tat ca nang luring tu Gibbs cUa no qua trinh dat den the can bang D6 lon cUa AG phu thu6c vao ski khac vg d6 16n dia Q va K Bang each chon cac gia tri trang thai chuan cho Q, ta thu duoc bien thien nang Wong Gibbs chuan (AG°), la tong nang Wong Gibbs giai phong di diem bat dau dia trang thai chuan den diem ket thlic tai trang thai can bang Khi moi Ming d6 Id 1M (hay moi alp suat la latm), Q bang 1, nen: AG° = RT1n1 - RT1nK hoac AG° = -RT1nK (7-63) (Thong to nhu phudng trinh (7-51) da duoc rut cho Kp phia tren) Moi quan he rat quan cho phep chimg ta tinh Nen thien nang Wong Gibbs chudn (AG°) cua mot phan ling tii hang so can bang K va ngtioc lai Vi AG° c6 quan he logarit v6i K, nen moi ski thay doi nh6 v6 gia tri AG° cling anh huang lon den gia tri cUa K Bang 7.5 cho biet cac gia tri cua K Wong ling voi khoang Wen thien cac gia tri AG° (51) Bang 7.5 Tuzing quan gicla ziG° va K 298°K AG° (kJ) K Y nghia 200 x 10-35 Co ban khOng c6 phan ang thuan; phan 100 x 1018 ang nghich coi la hoar' toan 50 x 10-9 10 x 10-2 1 x 10-1 Phan timg thuan va nghich cá toc 0 bang -1 1,5 -10 50 -50 x 108 -100 x 101 ' Phan (Mg thuan coi hoan toan; co ban -200 x 1035 kh6ng có phan ang nghich Tat nhien, hall het cac phan ring khong bat dau veil tat ca cac phan dieu ki5n chuan dila no Bang each thay mii quan 115 gifia AG° va K [phridng trinh (7-63)] vao bi5u thric AG [pinking trinh (7-62)], cluing ta thu dridc -bi5u thric có the alp dung cho bat di nang d6 khai dAu nao: AG = AG° + RT1nQ (7-64) - Bai than dp dung pinking trinh (7-63) va (7-64) Tra lai vi du dd bie't ve sif oxy hoa SO2 san xuat acid sulfuric (chtiong 6): 2S02 (k) + 02 (k) 2S03 (k) O 298°K, Vic d5 phan ling qua cha.m, vi the ngridi ta tien hanh a nhikt d5 cao hdn Hay:
Cho biet AG 2°,8 = -141,6 kJ/mol va AG y73 = -12,12 kJ/mol
Gicii: (52) ( —141,6 kJ / mol x 1000 J /1 kJ 8,31 J /mol.() K x 298 °K Vay, Kp = e57'2 = 7.10' + C 973°K, s6 mu la: ( —12,12 kJ /mol x 1000 J /1 kJ 8,31 J /mol.() K x 973 'K Vay, Kp = = 4,5
so3 0,10 -AG°/RT = -AG°/RT = • QP = Ps D = 4,0 jp so2 x 02 0,50 x 0,0 \= 57,2 \= 1,5 + Vi Qp < Kp d ca hai nhiet nen c6 nhigu SO3 tao hon, cho den Qp Wong ducing vdi Kp Tuy nhien, a 298°K, phan itng hAu nhti chuygn vg ben phai (chigu thuan) truck dat trang thai can bang; a 973°K, phan iing chi dich chuygn mot chat sang chigu thuan c) Tinh AG d trang thai khong chuan: + Cj 298°K la: AG298 = AG 298 + RT1nQp \= -141,6 kJ/mol + (8,31 J/mol.°K x 1kJ/ 1000J x 298°K x 1n4,0) = -138,2 kJ/mol + CS 973`)K la: AG973 = AG (,)73 RT1nQp \= -12,12 kJ/mol + (8,31 J/mol.°K x lkJ/ 1000J x 973°K x 1n4,0) = -0,91 kJ/mol Thao luan kgt qua: d6i vdi cac ap slat ban d'au ii 973°K, qua trinh chi vita du xay tit phat (AG = -0,91 kJ/mol) Tuy vay, to van tign hanh phan iing nhiet d6 cao ding vOi mot chat )(tic tac a tang ma.nh t 6c phan ling thvc to san xugt (mac du san Wong cao hdn d nhiet thap, nhung t6c phan ling lai qua cham) — Thuat ngit tit phat va khong ttt phat d6i voi cac phan itng thuan nghich Xet phan itng hai chigu tang quat A B, c6 hang s6 can bang (53) Nang lu 'cing ty ' (G. ) 1 G° < Cant bang h6n hop G = pilot (AG < 0) Tit tra di, phan iing la khong tv phat (AG > 0) Gia this chung ta bat dau v6i chat B tinh khiet thi phan ling cling se dat ten can bang al ca hai trvang hop, nang Wong tV Gibbs giam phan ling tien trien den gia tri cvc tieu a trang thai can bang Neu chnng ta bat dau vdi chat A tinh khiet, binh phan ling chfia hau het chat B phan ling ket thuc, ta not rang phan ttng theo chieu to A > B la tii Oat Thong tit, neu bat dau veil chat B tinh khiet, phan ling cling ket thlic hau het chat B c6 mat Mac du chi mot lvong rat nh6 chat A tao de thoa man trang thai can bang, ta not rang phan ling nghich tit B —> A la khong tit phat vi no tien trien rat it v6 hitting Doi vdi phan ling tang A B (bat dau vdi tat ca cac phan C1 trang thai chuan), G (B) < G (A) , nen AG° < 0, tvong ling vdi K > va vi vay phan ling tai din bien theo chieu sang phai Bay gia ta 14i xet phan ling C D, K = [D]/[C] < (hinh 7.11B) Neu bat dau vdi chat C tinh khiet, he giai phong nang lilting tit Gibbs mot cach tit phat den dat trang thai can bang Tuy nhien, tai thin diem nay, phan ling nghich (D > C) tien trien nhieu hdn v6 phia ngtioc va la tv phat, phan ling thuan (C —> D) khong tien trien nhieu va la khong tit phat Vi vay, thuat phcin zing tu' phcit cm cap den mot phcin zing tr(ii &in (chie-m u'u the ho'n) lie phia tao sdn pheim, cha khong nhifit thiet phdi li mot phcin zing hoan town Chat A Mgt dO cua phan Crng Chat B Chat C Mac dm phan Cing Chat D tinh khigt A tinh khigt tinh khigt B tinh khigt Hinh 7.11 Toting quan giCia nang lu'ong tv Gibbs va mac c10 coa phan Ong Nang lu'ong to' Gibbs cela he va mt-ic'dO phan Ong du'oc minh hop cho hai phan Ling tong quat co gia tri di' a hang so" K rat khac d A la phan (mg A B, G°A > G(E , vay K > va (54) 2.5 Cac dung cita bi'At thiic tac dung khol l>Idng va hang -s6 can bang 1/ Nhu da biet, can bang the hoa jai cUa cac eau tit he phan -tang dan den can bang hod hoc Vi the, khong gieng nhu dinh luat tec (phuonk trinh tec do) phai duoc xac dinh bang thuc nghiem, BTTDKL chi di a tren pinking trinh da can bang Bieu thfic la tY) le cac s6 hang nhan vdi nhau, m6i s6 hang duoc luy thita vdi he s6 hop fir& (he se ty Wong) pinking trinh phan itng (cac phuong trinh ly thuyet va cac vi du cu the phia tren da minh hoa dieu nay) 2/ Met gia tri K d4c trUng chi c6 nghia no lien quan den met pinking trinh Cu the da can bang Neu cac he se cua pinking trinh da can bang dttoc nhan vdi met thita se; chung thi thita s6 d6 tr6 s6 mu cho BTTDKL va cho hang se can bang di kern vdi no Chang han, tra lai phan Ung (7-50), neu nhan vdi thita so n, ta c6: n [ aA + bB eE + fF , BTTDKL se la: [E]e [F]t' n [i6i]a [B]b Vi du: (a) N2 (k) + 3H2 (k) 2NH3 (k) Kc = 2,4.10-3 & 1000°C 7- ( [NH3]2 [NH J2 vik: Qc = va K c = JN2][H2]_ /IA Neu: (a) x —1 3 — 2 NH3 (k) + H (k) (k) , thl 3 \ 1/3 [NH312 ( [NH312/3 Q'C = JN21 [H2 13 ibd [N 2]1/3 [H 2]ibd [NH]213 va K c = (Kc) 1/3 = = (2,4.10)1/3 = 0,13 ■[N2 ]1/3 [H ]ieb Neu tiep tuc, ta c6 the nhan phan Ung (a) veil he se n bat kS7 va tim duoc cac hang se; Kc c6 cac gia tri rat khac [thoat dau c6 cam giac rang, chUng ta da lam thay doi raw cUa phan itng (the hien qua thay doi gia tri K) chi bang cach thay doi he s6 can bang cila phUong trinh Cam gide ay that slat khong dung Bdi vi, nhu da not tren, moi gia tri K gan lien vdi met phan itng cu the Q va K la nhung dai Wong khue-ch phu thu(ic vac Wong chat nen khong the so sanh truc tiep gifia cac phuong trinh khac nhau] Q' = , va K' = (K)" (7-65) (55) Qcking = Qc(1)*Qc(2) LN 1/4-1 re\ KTryi nvi- rn • L.LN._, _12 L■ /2J LIN 2J 1.`-'212 (1) N2 (k) + 02 (k) 2NO (k) K c = 4,3.10-25 (2) 2NO (k) + 02 (k) 2NO2 (k) Kc2 = 6,4.109 Phan Ling tong: N2 (k) + 202 (k) 2NO2 (k) [NO]2 [NO2 ]2 = [NO2 ]2 3/ BTTDKL va hang s6 can bang cila phan ling thuan (th) va phan using nghich (ng) có quan he nghich ciao: Q(th) = 1 va K(th) = (7-66) Q(ng, K(ng) Chang han, n6i tiep vi du phia tren, phan ling nghich cila (a) dIfOc viet: 2NH3 (k) N2 (k) + 3H2 (k) ([N2 1[1-113 1 thi KC(ng) = ENH312 \= 416,7 a 1000°C 2,4.10 Kc 4/ Nhii da thay, Chung ta vie't BTTDKL va BTHSCB ma khOng can biet pinking trinh phan ling bieu thi giai doan phan ling hay phan ling tang gom nhieu giai doan Bai vi, d TTCB, chi cac he s6tY) hiring moi có vai tra Neu phan ling la tang cila hay nhieu Phan ling, thi BTTDKL hay BTHSCB se bang tich cac bieu thitc cila cac giai doan: Qtong = Ql•Q2• C 3• • • Va Kt6ng = (7-67) VI du: &Ong cd cua xe co, t° — 100°C, N2 -yd 02 tao NO, sau phan ling tiep voi 02 tao NO2 - mot chat nhigni d8c hai Hai buoc phan Ting la: KC tiing K ci = (4,3.10-25 ).(6,4.109 ) = 2,8.10-15 5/ Neu cac phan cua phan ling cling pha thi he dat toi TTCB &Ong the Neu cac phan la khac pha, he dat tai TTCB di the Trong tniang hop sau, mot hoac nhieu phan ciia he la chat lOng hay chat ran Chang han, xet can bang da voi phan hug' voi sang a — 900°C: CaCO3 (r) CaO (r) + CO2 (k) [CaO] [CO2] theo quy tac viet BTTDKL, ta c6: Q c = Tuy nhien, chat [CaCO3 ] (56) trong the tich 1L chat ran) Mat khac, the tich chat ran rat it thay de;i theo nhiet V6i cac IY do, n6ng chat ran la hang so Cling t dng tit dea voi chat lOng tinh khiet Vi chung ta chi quan tam den cac ang thay doi phan fing tien den TTCB, nen cac se" hang n6ng cila chat ran vb chat 'Ong dnoc lien hop lai hang so/ chung Chat ran va long tinh khiet khong c6 mat BTTDKL va BTHSCB Chang han doi v6i phan Ting tren thi: [Ca03] \= QC • = [CO2 ] [CaO] DU hiong CaCO3, CaO di mat la bao nhieu thi BTTDKL cna phan itng cung chi tticing &tong vdi ang CO2 6/ Cho den day, chung ta luen viet cac gia tri cua Q va K ma khong kern theo don vi, cluing chi la nhUng so Dieu c6 ngan ge'c tit khdi niem the hod cila mol ly tvang Cdn nhac lai rang, mai so- hang BTTDKL (hay BTHSCB) bieu thi tSi le dm luong chat &toe cila met chat (n6ng mol/L hoac ap suat) so v6i Wong chat trang thai chudn dra no (1M hoac atm) • 1,50M Vi du: N6ng 1,50M tr6 thank = 1,5 Thong tu, ap suat 0,75 1,00M atm tr6 = 0,75 Vi cac se" hang khong don vi, nen theo Q va K cang khong c6 don Khi bleu thi Wong chat ducic (Pi, Ci, N) bang hoat de hang so can bang phai dnoc viet la: K = e f aE • aF a b aA 'aB (7-68) aA, aE, aE, aF la hoat (khong don vi) dra cac chat A, B, E, F tai th6i diem phan ling dat den TTCB 2.6 Giai quygt nhiYng van de dinh hicing lien quan dgn trang thai can Wang 1/ Xdc dinh hang se' can bang - Neu lnong cac chat d TTCB da biet (nha cac phep phan tich dinh luong), K de clang duoc xac dinh (57) H2 (k) (k) 2HI (k) O TTCB, tim thay binh phan Ting có 1,80 mol H , 1,80 mol 12 vb 0,520 mol HI Minh K cua phan ring Gicii Luang cac chat d TTCB duiic biet theo mol nen phai chuyen ve n6ng d6 mol/L: [H2] = 1,80 mol/1,50 L = 1,20 M Turing tg, [I2] = 1,20 M va [HI] = 0,347 M Day la neIng cac chat a TTCB nen thay vao BTTDKL to c6 Kc, va tinh diicic: [HI]2 0,3472 K \= = 8,36.10-2 [H2 ][12 ] 1,20.1,20 — Neu mot s6 gia tri a TTCB chua &Toe biet thi phai xac dinh cac gia tri ay tru6c, sau tim K Vi du: M6t binh da rut khong chiia mot Wang nha b6t graphit (carbon) va duicic nung nOng den 1080 K, sau them CO2 toi alp suat 0,458 atm Trong he xay phan iing tao CO Khi slat TTCB, ap suat -Using binh la 0,757 atm Tinh K cua phan Gicii Thong thuang giai quyet theo trinh ti sau: + Viet phan iing da can bang: CO2 (k) + C (r) 2C0 (k) + Viet BTTDKL TTCB de tim K: ( P2 Qp = co co, Ab \= K p Cac s6 lieu d'eu cho d dang atm nen K can xac dinh la Kp C(r) khong c6 mat Qp + Lap bang phan iing (ghi: Wang ban dau dia chat dau va san pham/su Bien dooi cac dai Wang ay/va cac dai Wang a TTCB) bang cach &at x la so atm dm CO2 da phan iing (giarn di) a tao san pham Ap suat P (atm) CO2 (k) + C (r) 2C0 (k) Ban dgu 0,458 Bien d6i -x +2x (58) Giai thich bang: mol CO2 phan *rig cho mol CO tao thanh, nen x atm CO2 phan iing se cho 2x atm CO tao Viet -x vi CO2 la chat dau se mat di (giam) qua trinh phan ling den TTCB; +2x vi CO la san pham Bie't Pte;ng nen xac dinh duoc x theo dinh lust Dalton [phuong trinh (1-18), chtfong 1]: Prong = 0,757 atm = PCO, PCO (6) = (0,458 atm - x) + 2x x = 0,299 atm Tii gia tri x tim dtioc, xac dinh ap suat rieng phan d TTCB: CO, (cID) = 0,458 - x = 0,458 - 0,299 = 0,159 atm PCO (cb) = 2x = x 0,299 = 0,598 atm Thay cac gia tri vao Qp tim chicic Kp: Qp = ( D2 \ CO co2 0,5982 \= 2,25 = K p 0,159 [Nha hos hoc can cam nhan hay doan duoc ket qua so bO trtioc tinh toan theo cac phtiong trinh Chang han, d day truoc tinh Kp, to dti doan: ne'u Kp rat lon thi hau nhu tat ca CO2 chuyn CO, nen PuIng se gap doi ap suat ban dau 0,5 atm x atm) Ngtioc lai, neu Kp rat nhO, hau nhu khong có CO dutoc tao thanh, nen ap suat cuo'i cung cua he (Prom) gan vOi ap suat ban dau 0,5 atm) B6i vi, ap suat cu6i cling ciia he nam khoang cac cuc tri (Pto,„g thuc da cho bang 0,759 atm), nen Kp tim thay phai có mot gia tri trung gian Dung nhu ke't qua da tinh, Kp = 2,25, khong qua ldn hay qua be] 2/ Chuye'n doq gifia Kp va Ke Vi du: Tinh Kc cho phan ling sau: CaCO3 (r) CaO (r) + CO2 (k) Kp = 2,1.10-4 (Ci 1000K) Gicii Co mol kill ben v6 phai, khong có mol nao ben v6 trai, vi vay theo (7-54b): An = - = Tinh Kc theo phuong trinh (7-59): Kp = Kc.(RT)1 = Kc = Kp.(RT)-1 Kc = (2,1.10-4).(0,0821 atm.L x 1000K)-' = 2,6.10-6 mol.K (59) Vi du: Can bang giiia nitric oxyd, oxy va nitrogen dtioc in6 to bang phtiOng trinh sau: 2NO (k) N2 (k) + 02 (k) , Kc = 2,3.103° (6 298K) Trong quye'n: P0 = 0,209 atm va PN2 = 0,781 atm 'Dinh dp suat rieng phan cila NO (met dec gay o nhiem mei truCing) TTCB khong ma nguai hit th6 hang Gicii Vi (kilo = 0, nen theo (7-60) thi: PN, • Po 0,781 x 0,209 Kp = Kc = = = 1:1 PN20 PNO = 2,7.10-16 atm - Xac dinh ang d TTCB tii ang ban dau va Kc Vi du: Miic bion de'i CO va H2O CO2 va 112 chicic sii dung a die'u hoa hon hop nhien lieu Neu cho 0,250 mol CO va 0,125 mol H2O vao binh phan ling 125 mL d 900K thi phan caa h6n hop d TTCB la bao nhieu? Bie't Kc = 1,56 Gicii Phan ling da can bang la: CO (k) + H2O (k) CO2 (k) + H2 (k) BTTDKL: Q c = [CO2 ] [H2 ] [CO] [H 20] Tinh ang ban dau cim cac chat dau: 0,250 mol [CO] - = 0,125 L 2,00 M 0,125 mol [1120] = - 1,00 M 0,125 L Lap bang phan ling: dat x = ang dO da phan fing N6ng (M) CO (k) + H2O (k) CO2 (k) + H2 (k) Ban d6u 2,00 1,00 0 Bi6n d6i -x -x +x +x (60) Thay cac gia tri a TTCB vao Qc d6 có Kc da bi6t: Kc [CO2 ] [F12 ] x x x \= • = 1,56 [CO] [H2 0] (2,00 - x) (1,00 - x) x - 3,00x + 2,00 Sap x6p lai, thu doe clang phuong trinh bac 2: 0,56x2 - 4,68x + 3,12 = Giai plutong trinh nay, &toe x = 7,60 M va x = 0,73 M Gia tri x = 7,60 M khong coy nghia hod hoc vi no lon hdn nOng d6 ban dau Vi vay, x = 0,73 M, va tinh: [CO]C, = 2,00 M - x = 2,00 M - 0,73 M = 1,27 M [1120],b = 1,00 M - x = 0,27 M [CO2]th = [112],b = X = 0,73 M Kim tra lai xem cac gia tri vita tim citiOc có cho Kc nhti da bie't hay 0,73 x khong: K 0,73 = 1,6; ke't qua dUng vi 1,6 la pham vi lam 1,27 x 0,27 trOn dm 1,56 4/ Xac dinh chi6u huong cua phan ling va tinh ang dO d TTCB Khi chi cho bie't Wong cac chat dau thi &tong nhien phan ling phai ti6n trign ve phia san pham va bang phan fing ta dat dau am (-x) cho sit bie'n ct6i cac chat dau N6u ta bat dau vii mot hen hop bat kY g6m chat dau va san pham thi chidu hiking phan ling se chita re rang Khi ay, bat bu6c phai so sanh Q va K de xac dinh xem phan itng "trei" theo httdng nao vg TTCB Digu se cho bi6t, ta can crat x mang dau am hay dau diking bang phan fing Vi du: Hai phan cUa tii nhien (CH4 va H2S) can duoc nghien ciiu de tao cac san pham (CS2 va H2) dila theo phan ling: CH4 (k) + 2H2S (k) CS2 (k) + 4H2 (k) Trong mot thi nghiem, cho 1,00 mol CH4; 1,00 mol CS2; 2,00 mol H2S va 2,00 mol H2 chtoc trOsn 'An binh 250 mL a 960°C nhiet de nay, phan itng có Kc = 0,036
(61) Gidi
[CH4] = - 4,00 M 0,250 L TUong tit, [H2S] = 8,00 M; [CS2] = 4,00 M va [H2] = 8,00 M Tinh BTTDKL: [CS2 ] [H2 ]4 4,00 x 8,00 _ Q c 64,0 [CI-14 ] [H2 S]2 4,00 x 8,002 So sanh Qc va Kc: Qc > Kc (64,0 > 0,036) Vi vay, phan itng tien trien v6 ben trai (chieu nghich), ang d6 chat dau se tang va san pham se giam
Nong dO M CH4 (k) + 2H2S (k) CS2 (k) + 4H2 (k) Ban dau 4,00 8,00 4,00 8,00 Bien d6i +x +2x -x -4x 6 TTCB 4,00 + x 8,00 +2x 4,00 - x 8,00 - 4x Tinh x: WO [H2], = 1,76 = 8,00 - 4x = x = 1,56 M [CS2],b = 4,00 - x = 4,00 - 1,56 = 2,44 M [CH4]Cb = 4,00 + x = 4,00 + 1,56 = 5,56 M [H,S],b = 8,00 + 2x = 8,00 + x 1,56 = 11,12 M Kim tra gia tri Kc tit cac gia tri vita tim dtioc: K r = 2'44 x 1'764 = 0,0341 0,036 - 5,56 x 11,122 5/ Si dung gia thiet de don giAn hoa phep tinh Trong nhieu tniCing hop, can cii vao dau hieu hoa hoc, to c6 the data them gia thiet nham tranh phai giai ph Icing trinh bac hoac bac cao hon (62) [chat ddu]bd x [chat d'au]bd "=-,' [chat ddukb Gia thiet khong c6 nghia la x = 0, vi nhti the thi kh8ng c6 phan Ung Tieu chuan day la: net' gia thiet gay sai s6 :5_ 5% thi dtfoc coi la dung va goi Cat la thoa man gia thiet 5% (nhung nghien citu yeu cau chinh xac cao có the dat gia thiet khac nha hdn 5%) VI du: Phosgen la chat d8c chien tranh (cla bi cam theo Hiep U6c Geneva) phan huV bai phan ing: COC12 (k) CO (k) + Cl2 (k) Kc = 8,3.104 (Cr 360°C) Mall [CO], [C12] va [COC12] nhiing Wong sau day cua phosgen phan 1Vva dat den TTCB binh 10,0 L:
Gicii [CO] [C1 ] [COC12 tinh [C0C12]bd = 5,00 mol/10,0 L = 0,500 M Lap bang phan itng voi x = [COC12] da phan Nong dO M COC12 (k) CO (k) + Cl2 (k) Ban dgu 0,500 0 Bign d6i -x +x +x a TTCB 0,500 - x x x [COC12 cb 0,500 - x = K c = 8,3.10 Vi K nha, phan itng khong tien trien manh sang phai, nen gia thiet x << 0,500 M = 0,500 - x 0,500 M, theo = 8,3.10-4 0,500 \= 2,0.10 2,0.10-2 Kim tra gia thiet: x 100 = 4% , nha hon 5% VI vay, gia thiet 0,500 thing (hay thoa man gia thiet 5%) Q c = [co] (63) Tinh [CO]c, = [C12]6 = x = 2,0.10-2 M [C0C12L, = 0,500 - x = 0,480 M
Q C = r[C0][C12 ] = x2 \= K = 8,3.10-4 [COC12 ch 0,0100-x c N6u gia thie't 0,0100 M - x 0,0100 M va = 8,3.10-4 = x = 2,9.10' 0,0100 2,9.10-3 Kim tra gia thi6t 5%: x 100 = 29% > 5%, vay gia thi6t sai 0,0100 Phai giai pinking trinh bdc 2: x2 + 8,3.10-4X - 8,3.10-6 = , tim dtiOc gid tri c6 nghia: x = 2,5.10-3 M, va xac dinh: [CO]c, = [Cid = 2,5.10' M [C0C12]cb = 1,00.10-2 M - x = 7,5.10-3 M 6/ Lim y chung: + Bang phan iing la mot ky thudt c6 ich, ngdn gon ma toan canh, tranh dtioc nham ran, nhat la d6i viii nhiing bai toan c6 nhi6u dii lieu thuic nghiem + Cac bai giai dinh Wong cua muc 2.6, phia tren cua cac muc trU6c niia hoac cua muc con-ti6p sau la nhiing truang hop th.thng gdp thiic hanh hay nghien diu hod hoc, san xudt va ca tut nhien Can chit Y each vi61 cac chit so c6 nghia (xem Phu luc cuoi Quy6n nay) duoc th6 hien cac vi du da cho 2.7 Sly dich chuye'n can bang Nguyen 1Y Le Chatelier D'a'.c diem clang lieu y nhgt cua mot he can bang la kha nang chuy6n dich sang mot trang thai can bang moi cac di6u kien thay doi Chi6u hilOng chuy6n dich dia can bang duoc chi nguyen 157 Le Chatelier (nha Hod hoc Phap 1850 - 1936) Khi thay doi mot s6 cac thong s6 xac dinh trang thai can bang dia mot he thi can bang se chuyk dich theo chik cheing1ai su thay doi (64) D6i vOi can bang hod hoc thuong xay su thay d6i: thay d6i ve n6ng chat dau hay san pham, thay d6i vg ap suat hay the tich c-Cia he, va thay d6i ve nhiet Diia vao nguyen lY Le Chatelier, chUng to se thay re rang hdn nhung ski thay doi ay anh huang nhu the nao den trang thai can bang I Anh hu'Owg czta sa' thay dai nong coo den, can bing hoci hoc Xet can bang sau duoc thiet lap 523K: PC13 (k) + Cl2 (k) PC15 (k) Q c = [PC15 ] = Kc = 24,0 [PC13 ] [Cl, ] Vi Kc chi phu thu6c vao nhiet nen T = const (= 523K): + Neu tang n6ng PC13 ho4c Cl2 (cac chat dau) thi can bang se chuyen dich sang phai tao them PC15 (san pham) de giii Kc = const + Ly luan Wong tu de ket luan rang, can bang se chuyen dich sang trai (tao them chat &du) neu rut best n6ng dO PC13 hoa'c C12 khOi he, hay tang them n6ng PC15 vao he NMI vay, neu tang n6ng 110 cua mot phan, he can bang se chuyen dich theo chieu tieu thu bot phan Neu giam n6ng de) cila mot phan, he se chuyen dich theo chieu tao them phan He can bang hien chuyen dich theo chieu thong lai sli thay cloi n6ng Tuy nhien, khong loai trif dUcic hoan toan sti thay doi Chang han vai vi du dang xet, TTCB ban dau dtioc xac lap b6i cac n6ng de sau: [PC13] = 0,200 M; [02] = 0,125 M; va [PC1,] = 0,600 M, vi the: [PC15 ] 0,600 KC (TCB ban clAu) T = 24,0 [PC13 J [C12 ] 0,200 x 0,125 Neu them 0,075 M C12, can bang se chuyen dich sang phai de tieu thu (lam giam) n6ng C12, tang them [PC15], va met TTCB moi duoc thiet lap Thiic nghiem cho biet, i TTCB men [PC15] = 0,637 M; [C12] = 0,163 M va [PC13] = 0,163 M, nen: KC (TTCB moi) = 0,637 \= 24,0 0,163x 0,163 (65) [Cid tieu thu = ([C121TTCB ban dau 1C1.21 them vac)) EC121TTCB mdi \= (0,125 M + 0,075 M) - 0,163 M \= 0,037 M (< 0,075 M), nghia la kh6ng loai trii dUoc hoan toan n6ng d6 C12 mdi them vao 2/ Anh hu'Ong cua sr.! thay c of ap suat den, can bang hoci hoc Khi xem xet anh Inaing cua ap suat den TTCB, to chi quan tam den nhting he c6 mot hay nhieu thb.nh phan la Chat lOng va ran gdn khong chiu nen, vi vay thay doi ap suat it c6 anh twang Ap suat chi thay d6i thay d6i n6ng cUa phan khi; them trd (khi khong tham gia vao phan ling) va thay d6i the tich binh phan ling TrUong hop anh In.fang thay d6i n6ng d6 cua mot phan cila he da dude xet phia tren TrUang hdp thay do' ap suat bang cach them mot tri vao he thi khong anh hu6ng den vi tri can bang Bai vi, the tich khong thay d6i nen tat ca n6ng d6 chat dau va san pham d TTCB van nguyen Mac du ap suat tong tang, n6ng d6 phan mol giam, nhung -CY le ap suat rieng phan cua san pham va chat dau van nhu triloc nen vi tri can bang khong thay d6i Truang hdp thay doi ap sudt thay doi the' tich thu'eing anh hu'O'ng reit nhi& tdi vi tri can bang, vi thay d6i the tich clan tdi ski thay de;i n6ng d6 (la s6 mol tren L the tich cua binh chfia): sti giam th4 tich binh chiia lam tang n6ng d6 va su tang the tich binh chiia lam giam n6ng d6 Theo phucing trinh (7-59): KP KN (Puind cAbn thi ap suat khong anh ht ang den Kp, nen: + Neu An > 0, tang P KN phai giam, nghia can bang bi chuyen dich sang trai (phia it mol hdn) de ch6ng lai sti tang ap suat Nguoc lai, giam P, can bang se chuyen dich sang phai + Neu An < 0, P tang KN phai tang, nghia la can bang bi chuyen dich sang phai (phia it mol hon) de lam giam su tang ap suat Nguoc lai, giam P, can bang se chuyen dich sang trai Neu An = 0, ap suat khong lam chuyen dich can b.'ng Tom lai, neti he can bang c6 sit chenh lech s6 mol gifia cac chat dau (66) It hdn; giam ap suit, can bang chuyen dich ye phia có s6 mol nhieu hon Dieu phit hop vdi nguyen VT Le Chatelier: he can bang hien chuyen dich theo chieu thong lai sit thay de2i dp suit 31 Anh hu'Ceng caa sa' thay ctdi nhi0 coo sten can bcing hod hoc Trong stl thay d6i, chi co nhiet lam thay d6i hang so can bang K Tit phtiong trinh (6-60): dG = VdP - SdT , P = const thi: aG \ \.„aT p _-s (a(Aw aT )p (7-69) Thay (7-69) vao (6-52), thu dtioc: AG = AH + T a(AG) aT p Chuyen ye (7-70) va chia ye cho T2, to co: T( a(Aw _ AG aT p AH T T2 (7-70) (7-71) Ve trai ciia (7-71) có clang tong thlic co ban cila vi phan (7-71) trO thanh: a ( AG \ AH aT, p T2 Cac pinking trinh (7-70) va (7-72) nhiTing clang khac cua phudng trinh Gibbs - Helmholtz Xet d trang thai can bang va thay (7-72) vao (7-51), thu duoc: AH" aT p0 RT2 (7-73) Day la phtiong trinh ding dp Van't Hoff, theo do: Neu phan ling la thu nhiet, AH() > 0, thl T tang K1 se tang (deng bien) Dieu có nghia tang nhiet de, can bang chuygn dich sang phai tao nhigu san phm hon (co the xem nhiet la met phan cua cac chat dau, nen tang no, can bang chuyen theo chieu giam no, tilt sang phai) VdU - UdV v2 , nen (67) Neu phan ling la toa nhiet, OH() < 0, thi T tang, Kp se giam (nghich bien), can bang chuyen dich sang trai (6 day, xem nhiet la mat san pham, nen tang no, can bang chuyen theo chieu tao nhieu chat ddu hon, tiic chieu nghich) Trong khoang hep cila nhiet tit T1 den T2, xem AS° va AH° khong d6i thi phuong trinh (7-73) trii thanh: T2 T, 1 1 - AH fdT K fdlnK p = in T = AH (7-74) T R J, T2 T K T, R TI T2 j Xet plutang trinh Van't Hoff (7-74), ta de dang rut ket luan gi6ng nhii tren Mat khac, neu biet gia tri hang s6 can bang KT a nhiet T1 va hieu iing nhiet cua phan ling (thuang dung dU lieu d di6u kien chuan T = 298 K), ngiidi ta c6 the xac Binh KT, d nhiet T2 nao Ngitac 10, biet gia tri cac hang s6 can bang d nhiet khac nhau, ta c6 the tInh dtiac AH° cita phan ling (chu AR' tinh bang Jun, thi R = 8,314 J.mo1-1.1C-1) Tom lai, anh huang cua nhiet den he can bang tuan theo nguyen lY Le Chatelier: chieu chuyen dich can bang la chi& chdng lai su' thay ddi nhi0 4/ Su thie-u yang anh hu'a* caa chdt xac tac O muc 1.7 phia tren ta da biet chat xtic tac lam tang t6c phan ling lam giam nang Kiang hoat hod, vi vay lam tang phan iing thuan va phan itng nghich voi ding mite Theo do, chat )(tic tac khong lam thay de>i vi tri can bang Tuy nhien, ta se thay la chat )(de tac gift vai tr6 chit ch6t de t6i ttu hod v6 nang Wang va thai gian cho mat he phan 5/ Ong dung thu'c to cac nguyen tac chuyen dich can bang (68) N2 (k) + 3H2 (k) 2NH3 (k) Aii (p) t, = -91,8 kJ [Hang nam, 110 trileu tan NH3 dtioc san xuit theo chu trinh Tinh tren don vi mol thi amoniac dtioc dig tao nhigu hdn bit ky hop chit nao khac Hon 80% san Wong NH3 clUng lam phan bOn (ngn nong nghiep tien tign sii dung phan bon clang NH3 long duoc nen va phun truc tiep vao dit) Cdc ling dung khac ciia NH3 g6m: san xuit chit no, HNO3, nylon, nhigu loai polymer; lam chit on Binh cao su, chat lam lanh, chit lam sach; tang hop cac chit lulu co va duoc phim] Chu trinh Haber la vi du dien hinh v6 dp dung nguy8n lY chuygn dich can bang Xem xet phan iing d TTCB, to thiy có cach de dat t6i da san Wong NH3: - Gidm [NH3] bang cach lien tuc rut NH3 he phan ling de can bang luon chuygn sang phai tao san phdrn (NH3) - Tang cip suit cac la chit diu (N2, H2) de can bang chuygn dich manh vg phla tao s6 mol it hdn - phla tao san phA:m (NH3) - Gidm nhiet dO Vi chigu phan fing tao NH3 la toa nhiet, nen giam nhiet can bang se chuygn dich theo chigu Tillie t6 san xugt can teci Liu ca, san Wong va t6c dO nhiet thip, san Wong cao nhung t6c dO lai cham Vi the, cac nha may san xuit amoniac hien dai boat dong d ap suit - 200-300 atm;'nhiet dO khoang 673 K (400°C), chit xuc tic g6m cac khoanh sat tinh thg 5-10 mm dtioc nIrang chim h(in hop nOng chay cua MgO, A1203 va SiO2 H8n hop (cac chit din) duoc nen lai (N2/H2 = 1/3 theo thg tich) va tiem vao bung phan fing nhiet va dp suit cao Khi hiSn hop chay qua )(tic tic, mot phin hiOng nhiet ma phan iing toa duoc cung cap de nang cao nhiet dO cua bung phan fing Hon hop can bang tao hic chlia khoang 35% the tich NH3 duoc lam lanh dgn ngung to NH3 clang ran (tI\TH3 = -33,4°C) va duoc rut Vi digm soi cila N2 (-196°C), cila H2 (-253°C) thip hon rat nhigu nen chUng van a dang va duoc bcim trei lai bung phan iing de tigp tuc chu trinh 2.8 Can bang chuygn hoa to bao (69) Enzym Enzym Dihydroxy- methyl valerat lsoleucin Threomin Acetohydroxy-butyrat Enzym I (Threomin dehydratase) Ketobutyrat Enzym Enzym Ketomethyl- valerat thanh sti chuyen hod cilia to bao Day la vo s6 kST tong cilia sit be gay li8n ket, tang hOp sinh •hod hoc va chuyen do2i nang Wong chide to chfic chu6i phan itng goi la &tong chuyen hod Mot s6 ditOng hien d6i cac polymer sinh hoc thiic an nhcing monomer cho xay dung nen tang co the: &tang, amino acid, nucleotid Mot s6 &tang sit dung nhiing phan tit nhe de tao nang Wong, va sau lai sit dung rat nhieu nang Wong de tao cac phan tit có chitc nang khac: hormon, chat dan truyen than kinh, cac phan tit khang the va cac biopolymer cua chinh to bao Ve nguyen tic, moi buoc ditOng chuyen hod la mot phan iing thuan nghich duoc xuc tac bdi mot enzym dac biet (xem xuc tac enzym, muc 1.7 phia tren) Tuy nhi8n, ta se thay, mac du có nhcing nguyen VT can bang nhu da thao luan teen, TTCB khong bao gia dat duoc nhfing &tang \Ted mot chu6i phan ling gem nhieu giai doan, san pham cua phan ling this nhat la chat dau cua phan Ting this 2, san pham cua phan iing this la chat dau cua phan ling this va cit the Chang han, xet &tang g6m budc chuyen threomin (1 amino acid phan cue, chila nhom OH) isoleucin (1 amino acid khong phan cuc, mach thang) nhu sau: uc the Threomin duoc cung cap tit mot viing khdc cua t6 bao, tao ketobutyrat nha xfic tac cua enzym (phan ling 1) Vi tri phan ling lien tuc chuyen sang phai bai vi ketobutyrat lien tuc duoc rut vao lam chat dau cho phan ling Tufting tu, phan ling chuyen sang phai vi san ph6m cua no la chat dau cho phan ling 1\46i phan ling ti6p theo deu lam dich chuyen vi tri can bang ciia phan ling tritdc ve huong tao san pham (70) Dieu quan la to bao dieu hoa n6ng dO cua san pham cuai cling cUa dudng Nhd lai rang, mot enzym xfic tac phan itng cd chat xam nhap vao vi tri hoat Ong Tuy nhien, n6ng dO cd chat rat Ion so vdi n6ng d6 enzym, nen neu khong có yeu to diet' hoa, tat ca cac phan itng to bao se xay vdi tac dO tai da lJoi veil day chuyen san xuAt cong nghiep thi day IA dieu 13-7 tUdng, vai mot sinh vat lai la mot tham hoa De diet' hoa tat ca cac san pham tao thanh, tac dO mat s6 giai doan chU chat duoc kiem soat b6i cac enzym dieu hoa, chnng, ngoai vi tri hoat &Ong thi chlia mot vi tri itc che tren be mat Cau true khong gian chieu cUa enzym lam cho vi tri fic die bi xam chiern thi hinh dang ciia vi tri boat dOng bi thay doi va phan ling khong duoc xuc tac nua Vi du don gian nhat ve kiem soat chuyen hod la san pham cuai cling ci'm &tong &mg vai tr.() phan tit lac ch6, enzym dieu hoa IA enzym xtic tac buoc dau tien Chng han, to bA.o tam thdi khong san xuAt protein thi isoleucin dude tang hop b6i &tang khong dude rut di Khi n6ng dO dm no tang len thi isoleucin se chiem vi tri fic che cua enzym va "dong during san xugt no mot cach hau hieu Qua trinh goi dieu hoa ngudc bang san pham cUa phan itng cuai Nhieu &long diet' hoa plific tap hdn theo nhung mo hinh khac nhau, nhung rat nhieu s6 van la cd che dieing tit dieu hoa nguoc Nhu vay, std dieu hoa cac &tang chuyen hod lai bat ngu6n Ulf cac nguyen 1ST cila thing (71) MUC TIEU 1 Neu ctinh nghia va each phan loai cac dung dich, ccic ndng 2 Gidi thich cac thong tin ye thcii ci a mot chat nguyen chat dilac ghi tren gidn dd pha 3 Trinh bay cac nguyen nha n ve lien k et va nhiet dOng hod hoc qua trinh hoa tan hinh dung dich 4 Van dung du'ac dinh luat phan bd, ctinh luat Henry, cac dinh luat Raoult va Van't Hoff cho cac loai dung dich de giai thich va giai quyet nhting van ctj tic thvc te: ChiIdng ski HINH THANH VA CAC TiNH CHAT CCJA DUNG DICH 1 NHUNG VAN DE CHUNG Vts SU HINH THANH DUNG DICH 1.1 Dinh nghia - Phan loai Cac h" phan tan: mot chat phan tan nhiling hat rat nhO vao mot chat khac lam mot he phan tan CO tat ca he phan tan (bang 8.1) Bang 8.1 Cac h0 phan tan He phan tan Vi du 1 K/K (kill ph5n tan khi) KhOng kW L/K (lOng ph5n tan khi) Suring mu 3 R/K (ran ph5n tan khi) Hai iod thang hoa; bui; khoi khOng 4 K/L (khi ph5n tan king) Nutic thien nhien hoa tan oxy; nuOc uong có gas (CO2) 5 L/L (I6ng ph5n tan !Ong) C6n nude; nhili Wang 6 R/L (ran ph5n tan king) Cac mu6i, during hoa tan nuac; huy6n phi; keo K/R (khi ph5n tan ran) Hydro bi hap phu platin 8 L/R (long ph5n tan ran) Hai nutic bi hap phu than hoat, silicagel (72) Theo nghia rang, ngtioi ta goi tat ca cac he phan tan nInt th6 la dung dich; chat phan tan thank nhang hat rat nhO (phan tit, ion, hoac mot tap hop cua chnng) goi la chat tan; moi truang phan tan goi la dung moi Vay„ dung dich g6m chat tan va dung moi Ngttai ta thtiOng quy Binh dung mei la eau al ma clang tinh khik no c6 trang thai tap hop giong nhii dung dich (vi du, dung dich nttdc cua cac mu6i, thi di nhien nti6c la dung moi) N6u ca hai cau tit (chat tan va dung moi) c6 trang thai tap hop nhti (vi du, rtiOu Ira mi6c), thi dung moi la cau tit c6 Wong lon hon - Thong thtiOng ngtfoi ta goi dung dich lot mot he phan tan ma dung moi la mot chat l6ng Dung dich 'Ong la he phan tan ph6 bi6n va quan nh'at to nhien va sinh quyen Gido trinh cling chi nghien cuu ki6u dung dich nhti the Dung dich ma dung moi la chat 16ng lai dtioc chia loai tuST theo kich tint& cua ti6u phan (hat) chat tan Bang 8.2 trinh bay sti phan loai Ira dac tinh cac dung dich lOng Bang 8.2 Ph5n loai cac dung dich long du'a tren kich thu'dc tau phan chat tan Loai Kich thu'dc ch'it tan Dac tinh dung dich Vi du cac chat tan • Dung dich th5t, Om: - Dung dich cac chat kh6ng dian ly (dung dich ph5n ti1') - Dung dich cac chat dian ly • Dung dich keo • H6n dich, g6m: - NH Wong (nhil dich), L/L - Huyen phO, he R/L < nm 1+100 nm \> 100 nm Chat tan kh6ng nhin thay du'oc kinh hign vi dian 0; di qua du'oc cac mang sieu loc va mang ban tham; khugch tan nhanh Chat tan khOng thay du'oc kinh hign vi thuting, nhu'ng c6 the phat hien kinh slat,' hign vi, thay du'oc kinh hign vi dian tif; lot qua giay loc thu'Ong, n1-fling kh6ng qua du'oc mang ban tham; khugch tan rat ch5m Chat tan nhin thay dutic cac loai kinh hign vi; kh6ng qua du'oc gray loc thu'ong, kh6ng tham tich qua mang ban tham; kh6ng khugch tan Cac ph5n to' oxy, glucose; cac ion don giAn Keo bac clorid (AgCl)n; polymer thien nhien ho5c tang hop c hat khoana' Cac hat phu sa; cac nht? tu'ong va huyen phu du'oc dung; cac to bao hong cau mai (73) met cluit thi dude xep vao dung dich keo, lon hon met chat lai dude phan loai la h6n dich Nhfing dung dich chiia chat tan tinh khiet &toe dieu the phOng Ulf nghiem hoac cong nghe dfing cho muc dich nghien an' hoac lam thuo-c Dung dich thien nhien, da.c biet cac mOi truang sinh hoc, deu la nhUng dung dich plific tap Vi du, scia Tang vat la met dung dich phlic tap, go'm 87 - 89% nuoc (dung moi); 2,7 - 4,5% lipid (a dang nhu tdong, to tach yang sila dung lam bo); 2,7 - 3,8% casein (la protid dang dung dich keo, c6 the tach rieng lam ph6 mat) va 4,5 - 4,7% lactose (duang sfia) cling voi cac muOi khoang, cac vitamin dang dung dich that) Mau nguai la met vi du khac v6 mot he phan tan bao gOm ca loai dung dich long dien hinh va rat plific tap Hang cau, bath cau, tiL cau la nhiing to bao mau, chiem 40 - 46% the tich mau, tao he phan tan th6 (11-6n dich) huyet tticing Huy& ttidng chiem 54 - 60% the tich mau (chi yeu la nude chiem 90% khoi ludng huyet ttiOng, &mg vai tr.() dung m8i) vita dung dich keo (vi chiia cac dai phan tit nhti cac albumin; protein; plific hop protein - lipid), vifa la dung dich that (vi chiia cac chat hoa tan la nhiing phan ti nhO: oxy; glucose; cac hormon, enzym; cac chat vo cd Nat, IC, Ca', Mg', Cr, HC032-, phosphat, sat, dOng, cobalt, selen ; cac chat can ba to bac) dao thai nhu CO2, ure, creatinin, cac acid va sac to mat ) Nhcing kien thfic trinh bay gido trinh chi' yeu la cho dung dich that, goi chung la dung dich He phan tan keo dude de cap ci chuyen de rieng 1.2 Cac each bie'u thi nong Bang 8.3 Cac loai nong de) Loai nong Ky hieu Dinh nghia + Phan tram theo kh6i litong (KL) + Phan nghin theo kh6i ludng + Phan tram theo thg tich (V) + Phan tram theo kh6i lu'ong-the tich + Phan nghin theo kh6i ludng-thg tich + Mol + Du'ong bong + Molan + Phan mol % (KL/KL) %o (KL/KL) % (V/V) % (KLN) %o (KL/V) hoac g/L M, mol/L N m X hoac NI; S6 g chat tan 100 g dung dich SO g chat tan 1000 g dung dich SO mL chat tan 100 mL dung dich S6 g (hoac s6 mg) chat tan 100 mL dung dich SO g chat tan 1000 mL (= L) dung dich SO mol chat tan L dung dich S6 dudng Iu'ong gam chat tan L dung dich S6 mol chat tan 1000 g (= kg) dung m6i (74) N6rg d6 la cach bieu thi phan dinh luong cua mot dung dich NO có the bieu thi Wong chat tan mot the tich xac dinh cila dung dich hoac luring chat tan mot khoi hldng xac dinh cila dung dich hoac cUa dung moi Lacing chat tan dung dich cang lOn thi n6ng d6 cang lon va nglioc lai Bang 8.3 tom tat cac loai nang thliang dtioc dung hod hoc va Y- Duoc DO% day.là mat s6 vi du cu the v6 cac loai nang d6 hay gap - N6ng d6 %, %o theo kh6i luong/khOi Wong: Vi du: Dung dich KNO3 10% c6 nghia la có 10 g KNO3 100 g dung dich Dung dich cac acid dac H2SO4, HNO3 va HC1 ban tren thi truang c6 nang d6 Wong ling bang 96%, 65% yd 36% BOi vi, the tich dung dich de dang hdn kh6i Wong, nen ngithi to thifang ghi kh6i Wong rieng kem theo cho loai dung dich nay, de chuyen d6i to khol hldng chat can lay sang the tich dung dich can dong Vi du, HC1 36% có D = 1,179 g/mL (6 20°C) Dung dich NaC1 9%o c6 nghia la có g NaCl 1000 g dung dich - N6ng d6 %, %o theo khol Itiong/the tich (thithing duoc viet g/100 mL; g/L ): Vi du: Dung dich glycerin 10 g/100 mL, glucose 50 g/L có nghia la co 10 g glycerin 100 mL dung dich, có 50 g glucose lit dung dich cho dung dich hiring Ting da ke - N6ng mol/L (M): Mol la mot Wong chat chlia s6 hat ding kieu cau trilc (phan tii, nguyen ti ion, electron, proton ) bang s6 Avogadro 6,022.1013 ThUang sii dung la mol/L, s6 phan tii gam/L Cac, dung dich c6 nang d6 mol bang thi chiia ding s6 Wong hat chat tan nhung the tich dung dich bang (chn ST: hat chat tan phai cling kieu can trot) Vi du: Dung dich NaOH 2M, nghia 1a lit dung dich có mol hay mol x 40 g/mol = 80 g NaOH Dung dich chila phenobarbital 0,001M Ira NaC1 0,1M, nghia la lit dung dich nhit the cal 0,001 mol x 232,32 g/mol = 0,2323 g phenobarbital (C12 H72N203 = 232,32) va 0,1 mol x 58,45 g/mol = 5,8450 g NaCl (M = 58,45) Trong lit dung dich NaC1 1M có mol x 58,45 g/mol = 58,45 g NaCl Xem NaC1 dien ly hoan toan cac ion, thi lit dung dich nhu the cling có mol ion Nat (23 g Nat) va mol Cl- (35,45 g CU (75) Enguycm Kheii hrong nguyen tir Vi du: Eoxy Hod tri 16 8 Vi du: EA,,* E so4- S6 ion fr dien ly tir mot phan tir acid 36,45 = 36,45 98 EH2S02 = 49 Kh6i lining phan tir base Vi du: E Fici - N6ng d6 &tong Wong (N): Vi du: H2SO4 0,5N la dung dich child 0,5 ducing hiving gam H2SO4 lit dung dich Khal niem during Wong dm chdt xudt phat tii dinh ludt &tong 1-acing dia Dalton ,neu nam 1792 (xem chtiong 1) Goi &tong hfc.ing mot chdt la E to có the neu cdc Ong thlic tinh E cdc phdn ixng trao d6i va oxy hod sau: Eacitl Ehase Kh6i ltrong ion I Dien tich ion I 27 9 96 48 Khoi lacing phan dr acid S6 ion OH- dien ly tir mot phan tir base 40 40 Kh6i luong phan tir mu6i IDien tich ion (throng hoac am)I x S6 ion (throng hoac am) 342 3x2 Vi du: E NaOH (76) Khoi luting tidu phan (phan tir, nguyen tir, ion) EOx(Kh) S6 electron nhdn (hoac cho) cua mot tidu phan Bang oxy hod (hoac dang khir) day, Eox(Kh) la during Wong cua clang oxy hod hoac cua clang Vi du, tim during luring dm chat oxy hod va chat khil.trong phan 2KMnO4 + 10FeSO4 + 8H2SO4 = 2MnSO4 + 5Fe2(SO4)3 + K2SO4 + 8H20 Can cit theo s6 electron ma met phan tii KMnO4 nhan bang va s6 electron ma mot phan tii FeSO4 cho bang 1, ta xdc dinh dtfoc dating luting cUa chat oxy hod la: EKNino4 158 = 31,6 5 va during Wong caa chat khit la: 151,8 \= 151,8 Vi hod tri cUa nguyen to, s6 H+ hay OH- dien ly dm acid hay base, se; electron nhdn hodc cho cua chat oxy hod hoac chat khii c6 the thay doi tuST theo dieu kien cua phan ling, nen duong ltiong cita met chat cling c6 nhting gia tri bi6n dei Dicing Wong met dai luting khong c6 this nguyen Trong hod hoc ngtioi ta thuong dung: + Diking tong gam ciia mot chat la kh6i Wong cilia chat bi6u dien bang gam Ira c6 tri s6 bang &tong Wong cila no + Mili &long luring gam, l(ST hieu mE, bang 1/1000 &tong Wong gam va lay don vi Main Wong la miligam Vi du, c6 cdc cong dr& tinh sau: EFeSO4 S6 during lu'cing/mol TraOng hop chat phan tan dung dich thi tit cac cong dr& tren c6 the suy ra: Khe luring chit (g/mol) Diking liking gam cilia chit (g/E) = SO during itking/mol Mili during luring gam cilia chit (mg/mE) = Kh6i luring chit (mg/mol) (77) Mili &Ring lacing gam cila chat (mg/mE) = S6 mili during lacing/lit Vi du: Biet lit huyet Wong cila mau ngi.thi có 100mg Ca' Tinh: a S6 mili &long Wong gam dm Ca' lit buy& Wong? b S6 miligam CaC1,.2H20 de pha 750m1 dung dich có n6ng ion Ca' wong &wing huyet Wong? Gidi: S6 miligam a E C a - ` 40 2 = 20 g/E hoAc 20 mg/mE ta có: 100 mg/lit 20 mg/mE = S6 mili &rang lacing/1ft \Tay, s6 mili doing Wong cUa Ca"/lit (huyet Wong): 100 mg/lit 5 mE/lit (huyet ttiong) 20 mg/mE b ta co: ECaCI,.211,0 147 1 x = 73,5 g/E hoac 73,5 mg/mE S6 miligam chSt/lit 5 mE/lit Nen, s6 miligam chat (CaC12.2H20)/lit = 73,5 mg/mE x mE/lit 367,5 mg/lit De pha 750m1 dung dich can: 750 ml 1000 ml N6ng d6 molan (m): N6ng molan khong bi bien doi theo nhiet d6, vi khac vdi th.4 tich, khol Fong dung moi khong phu thu6c vao nhiet d6 Vi du: Dung dich NaC1 0,173m dung moi nuoc, nghia la có 0,173 mol NaCl 1000 g mioc, chinh la dung dich NaC1 1% theo kh6i luring - N6ng d6 phan mol (X): Neu nA la s6 mol dung moi A va nn s6 mol chat tan B, thi ang d6 phan mol cua chat tan B la: 73,5 mg/mE = (78) X B n B 11 A n B va ang d6 phan mol cita dung mai A la: X A nA nA + n8 Hiking nhien: XA XB = Vi du: Tinh ang d6 phan mol cua cac chat dung dich g6m 142 g isopropanol (C3H7OH) va 58,0 g nti6c Gidi: 142 g C3H 7OH S6 mol C,H7OH = — 2,36 mol C3H7OH 60,09 g C1H 7OH/1 mol C3 H 7OH S6 mol nti6c = , 58,0 g H20 = 3,22 mol H2O 18,02 g H 0/1mol H2 SOmol mol C3 H 7OH 2,36 mol x c,H7ou = Tong so mol dung dich = 2,36 mol + 3,22 mol = 0,423 SO mol H2O 3,22 mol X H20 = = = 0,577 XC,H2OH + X H20 = 0,423 + 0,577 = 1.3 Can bAng pha Qua trinh hinh va nhang dac tinh ciia dung dich lien quan chat the den can bang va Nen d6i cac pha Quy tac pha cim Gibbs cho bie't quy luat chinh xac va tang quat ve mat nhiet Ong he hoc d6i vdi tat ca cac he can bang Cac khai niem va dinh nghia: + H" ddng the' he ma cac phAn khac cua no c6 ciing phan, ding tinh chat hod hoc va nhiet Ong + HO di the' la he ma a cac phan khac cua no thi khac ve thanh phan va cac tinh chat hoa hoc, nhiet dOng + Pha la tap hop cac phan d6ng the he c6 phan, tinh chat d6ng nhat va drfoc gioi han vdi cac phan d6ng the khac c4a he bai cac mat phan each ro ret (79) S6 pha he duoc ki hieu bang chit c1) He chi c6 mot pha = 1) la he delng the He chiia pha trO > 1) la he di the Vi du: Nttoc c6c la met he do'ng the, chi có met pha lOng = 1) Them cac cuc nuoc da vao c6c nuoc thi duoc he di the Om pha = 2): pha long nuoc va pha ran IA cac cuc nuoc da Hoac d sit phan huY' calci carbonat c6 can bang: CaCO3 (r) CaO (r) + CO2 (k) ton tai pha = 3) Om mot pha tao bOi CO,, met pha ran tao bai CaCO3 va pha ran this hai tao bat CaO • Cdu tic' la cac chat hod hoc cc-) mat he O cac vi du tren thi he pha (Ntteic H Ntteic da) chi có met cau tit la H2O; d hg pha (can bang phan huY calci carbonat) có eau tit la CaCO3, CaO va CO2 + So-cdu d'Oc lap, duoc ki hieu bang chit C, la so- cat' tit tot thieu du de mo to phan dia he N6i cach khac, la s6 cau tit t6i thieu ma da bigt n6ng cila chung la du de' xac dinh phdn cua he Ghia s6 Caul tit va s6 cau tit dOc lap (C) co mo'i quan he: C = S6 cau tit - S6 phtiong trinh lien he giiia cac cau tit (8-1) VI du, có can bang sau: PC15 (k) PC13 (k) + C12 (k) thi C = - = eau tit dOc lap, vi he g6m cat' tii nhung c6 pinking trinh lien he Oita chung Sa di nhu vay vi chi can bigt n6ng dia cau tit la c6 the suy n6ng d6 cua cau tit this nho vao hang s6 can bang cila he Theo do, phan cua ca he •duoc xac dinh TrUang hop giiia cac eau tit khong c6 pinking trinh lien he nao thi so- cau tit dOc lap C = s6 cat' tit he + Sdbiftc tu' do, Id hieu bang chit F, la s6 thong s6 Wang de cila he c6 the thay dOi tug Y ma khong lam thay de;i s6 pha va s6 cau tit cila cac pha Day chInh la s6 thong s6 doe lap cim he, chu y6u nhigt de, ap suat va n6ng clO — Quy tac pha: (80) F = C — + (8-2) day, F s6bAc tit (s6 th6ng s6 ct6c lAp cira he) C s6 ciu tit d6c lAp 4:1) la s6 pha va s6 dai dien cho thong s6 ben ngoal c6 the anh huang den he la ap suit va nhiet d6 VAy, doi vdi he can bang chi chiu anh hai ye'u to ben ngoai hp suit va nhiet d6 thi s6 134 t4 ciia he bang s6 ciu tit d6c lAp trif di s6 pha Ong voi Vi du: He mot cau tit mi6c, s6 CAI tit d6c lap cling (C = 1), c6 cac truang hop sau: + N6u he chi c6 nti6c lOng ((l) = 1) thi: F = - + = He c6 bAc tti do, nghia ta c6 the thay d6i tuS7 y nhiet (trong khoang tit 0°C den 100°C) va bat ki ap suit nap ma van khong lAm thay d6i s6 pha va ciu tit dia he D6 IA he nhi bi6n + N6u he can bang I\TV6c 'Ong Hoi nude = 2) thi: F = — + = co He bAc tit do, nghia thay d6i nhiet thi ap suit hdi dm he thay d6i mot each don tri: ap suit hdi nti6c bac) hoA can bang vdi nti6c lOng hoan toan xac dinh tai moi nhiet d6 Noi each khac, tai moi nhiet d'6 xac dinh chi c6 mot gia tri cua ap suit hdi bao hoa cira nti6c D6 he nhit bi6n + Neu he can bang co pha(CD= 3) Hai ntrac Nireic Nuot da thi: F = 1- 3+ = He khong c6 bAc tit nAo ca, nghia 1a nhiet va ap suit cira he ham toan xac dinh (6 T = 273,16°K va ap suit hdi nude P = 0,006 atm) Ngithi ta khong th6 tri can bang ne'u thay d6i du chi mot thong s6 nhiet hoac ap suit hdi Goi day he bit bi6n (81) Bang 8.4 Van dung quy ta"c pha (F = C - 0+ 2) cho cac he mot cau tit (s6 dOc rap C = 1) He S6 pha (0) S6 bac to (F = - cI) + 2) Chu giaiN1 du Khi, Long hoac Ran 1 2 3 F = F = F = - - - + = + = + = 1 0 hoac Khi R5n H5 nhi bign; g6m tat c5 cac didm ten viing Hoi, Lang, RAn dudc xac dinh bai thong so P, T tug H5 nh5t bign; g6m cac didm nam tron throng ph5n cach hal pha (vi du, cac duang OA, OB, OC tren hinh 8.4, 8.5) du xac dinh don trl hoac P hoac T H5 bgt bign; chi có mot didm la giao didm caa duang ph5n cach cac vOng, khOng có thOng s6 nao (P hoac T) du'dc thay d6i tu' (vi du, didm ten hinh 8.4, 8.5) Khi- -.' Lang Lang -, - Ran .,='-' Khi Ran -=. " Long Quy ta.'c pha the hien '6 plytiong trinh (8-2) c6 the duoc thiet lap nhu sau: Gia sii comet he can bang gorrl n chat phan b6 (1) pha De biet n6ng cac chat malpha ta chi ,Can biet (n - 1) n6ng do, bai vi nang cila chat lai dtioc suy tii hang s6 can bang T6ng so n6ng dac trUng cho he (1) pha 14 (n - 1)0, titc la c6 (n - 1)0 Wen s6 dec lap ben he Neu ke them Wen s6 dec lap ben ngoai la nhiet va ap suat thi t6ng cac Nen s6 clot lap se la (n - 1)I + Mat khac, trang thai can bang, m6i chat c6 - 1) pinking trinh lien he, bai vi m6i chat tit can bang voi no (ID pha (the hien qua cac hang se can bang, hoac qua can bang v6 the h.oa hoc - xem chuong 6) Vi du, neu he chi c6 pha thi chi c6 met 0-Wong trinh lien he cho m6i chat Neu he c6 n chat thi se c6 - 1)n phuong trinh lien he Khi gifia n6ng cac chat c6 k phttong trinh lien he (vi du, giiia cac nang phan mol c6 met phuong trinh lien he, vi X1 + X2 + + Xi = 1) thi t6ng s6 phuong trinh lien he gifia cac bien s6 dec lap se la - 1)n + k Ro rang la s6 bac to F cUa he phai bang t6ng so bien so dec lap trif di tang s6 phuong trinh lien he gifia cac hien s6 do, \Tay: F = [(n - 1)(ID + 2] — [(ta - 1)n + k] =- (n - k) — (1) + Theo he thitc (8-1), (n - k) = S6 ca'.0 tit (se- chat) - S6 phuong trinh lien he gifia cac eau tit = C la s6cau tii dee lap, vay: (82) Pinking trinh (8-2) da duoc chiing minh Luu y: he d diet' kien T = const hoac P = const thi phitong trinh (8-2) tr0 thanh: F = C - + ' (8-2') Neu he vita clang nhiet (T = const) vita Bang ap (P = const) thi: F = C - (I) (8-2") - Ban chit can bang va bien d6i pha: Cac that nghiem hang thuang tien hinh nhang he ma, nhiet va chit toa vao moi truing hoac &toe b6 sung lien tuc tit moi truang Bien d6i nhu the la khong thuan nghich Nguoc lai, he kin, cac bien d6i la thuan nghich dAtoi nhiing dieu kien xac dinh - Can bang LOng - Trong mot binh ho dung chit king, cac phan tii tren be mat se bay hdi cluing có dOng nang du lon de thing slic but ciia khol long Nang Wong duoc cap bai nhiet ciia moi truang xung quanh lam cho khoi king bay hdi den het Neu chit king duoc dung binh kind nhiet dO hang dinh, va gia thiet ban dill binh la chin khong, cac phan tit chit lOng teen be mat có dOng nang ldn se bay hdi (hinh 8.1A) S6 phan tit pha hdi tang, dp suit cua hdi binh ciing tang din O mot th0i diem nao do, s6 phan tit bay hdi tit pha king va s6 phan tit tit pha hdi ngung to tr6 lai pha king bang (hinh 8.1B) Tai diem nay, dp suit ciia hdi la hang dinh d nhiet da cho O mitc dO vi mo, hien Wong hoa hdi nhu thing lai, nhung d cap dO vi mo, cac phan tit van tach va ngung dong tren be mat chit Yang voi tY le bang nhau, he dat trang thai can bang dOng: Lang Hai Hinh 8.1C bieu din qua trinh vita mo ta (83) Hinh 8.1 A Trong binh kin a nhiet dO nhat dinh khong khi da dtioc hOt het, ap suet ban dau bang 0 Cac phan ter bay hal fa° ap suet tang clan tren mat chat Ong A B Khi s6 phan ter bay hdi bang s6 phan tit ngting dong hit lai be mat Ong, qua trinh bay hal dat trang thai can bang, ap suet hdi dat gia tri hang dinh ••••, r—■ sZ-4= Can bang V,, >= V ■ •= nn '110i gian D DO thi ap suet hdi - thai gian: ap suet hdi tang chOng nao t6c di) bay hdi (Vbh) Ion hon t6c dO noing dong (V„d) d can bang, ap suet hdi 15 hang so vi cac t6c dO dO bang nhau Ap suet tai diem goi 15 ap suet hal ci) a chat long nhiat nhat dinh Ap suet hdi am met chat phu thuec vao nhiet do: not chung, nhiet cang cao, ap suet hdi cang ion la s6 phan tit c6 dong nang du len vtiot qua luc not phan tit cua chat rang cang nhi6u Nhti vay, hic cac phan tic (ltfc Van der Waals) cang yet, chat- lOng c6 ap suet hdi cang 16'n Hinh 8.2 cho they (84) Ap su it he ll mm Hg Hinh 8.2 Ap suet hal ham cu'a nhiet ch, d6i vdi ba chat long khac O nhiet nhat Binh (vi du 20°C) diethyl ether co ap suet hal Idn nhat va nu'dc 15 nho nhat, &Ai vi 6 diethyl ether Ivo Van der Waals nho nhat, con nu'dc la manh nhat Du'Ong nem ngang • ti:r 760 mmHg chi nht7ng dam sOi caa cac chat lOng, la nhiet tai ap suet hal bang ap suet quydn mut nu'dc bier?) 20 40 60 80 100 t toot (0c) Sti tilOng quan khong tuye'n tinh gifia ap suet hdi va nhiet (hinh 8.2) duoc bieu thi qua phtiong trinh Clausius - Clapeyron: — AH hh ( R T day, P ap suet hdi (mmHg, torr) T 1a nhiet dO tuyet d6i (K) AHhh 1A Enthalpy hod hdi, nhiet hod hdi, nang luong can thie't de chuyen mol cdc phan tit chAt 'Ong hdi R IA hang s6 kill (8,314 J/mol.K) C IA mot hang s6 Phtiong trinh (8.3) có the bi'41.1 din &fang thA.ng (vi du cho rnioc va diethyl ether hinh 8.2) nhu tren d6 thi 8.3 DO thi cho thgy moi quan he gifia 1nP va 1/T theo plytiong trinh y = mx + b, day y = 1nP, x = 1/T, m (dO d6c) = -AlThh/R va b (tung dO y x = 0) = C Hinh 8.3 DO thi tuye'n tinh caa tu'dng quan ap suet hdi - nhiet dO Phuring trinh Clausius - Clapeyron cho mot thang neu bleu dien tren thi quan he InP va 1/T Cac d6c (-L1Hhh/R) cho phep xec Binh nhiet hoe hdi caa hal chat long Ltfu k /à dO d6c rat Ian (dung cli:rng) do7 vdi ntrdc vi AHhh cua nu'dc Ion fon nhieu y a_ Nuoc Diethyl ether t/T (85) Phitang trinh (8-3) va de., thi (8-3) cho phep xac dinh AHhh chat Tuy nhien, xet mot cap diem va lay hieu s6 gicia chung, ta c6 the xac dinh AHhh ma khang can dUng den de thi, vi ay phlidng trinh (8-3) ditdc P, OH hh \= 131 R 1 \ AH hh (T, - T1 ) RTI T2 (8-4) Vdi pinking trinh (8-4), da biet AHhi„ ta c6 the tinh dltdc dp suat hdi (P2) d nhiet dQ bat kY (T2) hoac tinh duoc nhiet dQ d alp suat bat kY, n'6u &toe biet P,, T1 Vi du, biet ap suat hdi cita ethanol (CH3-C112 OH) d 34,9°C la 115 mmHg va AHhh ciia no la 40,5 kJ/mol, tinh nhiet (°C) di) suat hdi la 760 mmHg Gidi: Thay cac du lieu da cho vao phudng trinh (8-4), chi] Y sit dung hoac chuyen dm dung cac don vi phu hop voi cac dai hiring phuong trinh: 760 mmHg ( 40,5 x 103 J/mol \ 1 In 115 mmHg \ 8,31 J/mol.K T2 (34,9 ()C + 273,16)K 1,89 T2 = \= (- 4,87 350 K x103.K-' — - (3,247 x10-3 )K T, Chuyen T2 °C: T2 = 350 K - 273,16 = 77°C Ethanol dat ap suat hdi 760 mmHg (bang ap suat quyen) tai nhiet dQ 77°C Day cling chinh la nhiet dQ soi dm ethanol d dieu kien thLidng (nhiet dQ soi cua cac chat se thao ludn tiep sau) Tra se; tay hod hoc, ta tim thay t's (ethanol) = 78,5°C, khong khac nhieu so \Ted ket qua da tinh theo pinking trinh cua Clausius - Clapeyron a tren (= 77°C) Quan he gifia rip suat hdi va nhiet dQ soi: he ha, ap suat quyen nen len be mat chat 16ng Khi nhiet dO tang, cac phan tit rdi khOi be mat 16ng tang nhieu va chuyen Ong tang nhanh ca toan kh6i chat long Tai nhiet dO nao do, &ling nang cua cac phan tit du lon de tao cac bong bong hdi not bO chat long, chat lOng soi CS nhiet dQ thap hdn, cac bong bong hdi se bi va trudc chting ditdc hinh vi quye'n có ap suat lein hdn ap suat hdi bong hdi Vdy, nhiet dO soi c eta mot chat /à nhiet dO ma tai ap suat hdi ceia chat bang ap suat ben ngoai Trong dieu (86) la hang so/ cho den pha long hohn toan bier' mat Si.i soi khong the xay he kin vi ap suat ben ngoai 1ai chinh la ap suat cua hdi thoat tit be mat chat 16ng, ma ap suat lien tuc tang nhiet tang Vi le de; sti soi khong phai la met hien tuong can bang Ap suat ben ngoai c6 the thay doi nen nhiet soi ctia chat cling thay dOi theo Nhiet soi binh thu'dng ctu'dc guy dinh la nhiet dO soi xciy tai c p suat khi gayer' tieu chua'n (760 mmHg = 760 torr, hoac 101,3 kPa) Tren hinh 8.2, &long nam ngang dirt net song song v6i truc hoanh chi cac diem soi cua ba chat 16ng Vi diem soi la nhiet de ma tai ap suat hdi cUa chat 16ng bang ap suat ben ngoai, b6i vay cluing to hieu cac dual-1g cong tren hinh 8.2 cling chinh la cac &tang bleu dien cua ap suat ben ngoai Wong -Cing voi nhiet soi Vi du, doing cong ciia nude cho biet nude soi 100°C tai 760 mmHg (Ung vdi mat bien); soi 94°C tai 610 mmHg (tren dinh nui cao) va soi 72°C tai 270 mmHg (tren dinh Everest cao 8850 m thuec vung nui Himalaia) Nguoc lai, nude cling c6 the soi tren 100°C nett tao ap suat ben ngoai len hdn 760 mmHg (nhu cac not hdp tiet trUng c6 van dieu chinh ap suat) — Can bang Ran - Lang: Cac tieu phan chat ran dao dong lien tuc quanh vi tri can bang Khi tang nhiet de, cluing dao dong kich liet hdn Den hic nao do, c6 met s6 tieu phan dat duce dong nang du 16n tach mang ltrdi tinh the va tra to do: s-ti nong chay bat dau Khi do, co nhieu tieu phan chuyen vao pha 16ng (nong chay), flirting ngudc lai cling c6 mot s6 tieu phan pha 16ng va cham vdi pha ran va tr6 cau true tinh the (goi la dong dac, hod ran, hoac ket tinh) Khi cac pha tiep xtic nhau, met can bang dong dudc thiet lap neu t6c de nong chay bang t6c de ket tinh Nhiet dO ma tai ton tai can bang goi la nhiet dO ming chdy (diem nong chdy), cling la nhiet dO dOng dac (dam dong c), chi khac chieu bien dea pha Ttiong to nhu diem soi, nhiet dO la hang dinh diem nong chdy chUng nao ca pha ten tai (nhiet cap vao he dudc chuyen dong nang cho cac phan ti but mang htdi tinh the su6t qua trinh nong chay, chic khong phai de tang nhiet de cUa he) VI chat long va chat ran hau nhu khong c6 tinh chiu nen, nen alp suat chi có tac Ong rat nh6 den t6c chuyen dong cila cac tieu phan qua trinh nong chay hay (Tong dac Do vay, khac vdi nhiet de soi, nhiet dong dac chiu anh rat it b6i alp suat Di6u dude thay tren de thi ap suat (truc y) - nhiet de (truc x): su chuyen &di pha Ran - Long cua hau het moi chat la met dung thOng gdn nhu dUng dung, hdi nghieng sang phai nhiet de cao (dung OB, hinh 8.4) S6 di nhu vay, vi cac chat lOng chiem khong gian (the tich) nhieu hdn cac chat ran, nen dp suat cao (lam co the tich), cac tieu phan long can c6 (87) deng nang len hdn (-Lac la nhiet cao hdn) de tang khong gian, tang the tich (nguyen lY Le Chatelier) Chu Y: nu& la met n.goai le, se xet - Can bang Ran - Hdi: Cac chat ran not chung co alp suat hdi nha hdn ap suat hdi ciia chat long rat nhieu Thang hoa, hien Wong met chat ran bien dei trkic ti6p hdi, thtion.g hiem gap, vi cac dieu kien v6 op suat va nhiet de de hien tuong xay la khong binh thuang cho hau het cac chat Chi mot s6 chat ran co ap suat hdi lend dieu kien thilen.g mei thang hoa, vi du da kilo CO2, met s6 chat diet mei mot hoac dang ran, iod Met chat thang hoa de hdn ming chay st.i lien hop gitia cac htc not phan tii va ap suat la khong du len de giii cac tieu phan lai gan nhau, Chung de tach khOi trang thai ran D6 thi ap suat - nhiet ye cho &tang cong Ran - Hdi chi anh htiang tren pham vi reng cua ap suat, nghia la &tong cong gieng nlru &long cong Lang - Hdi no dtioc keo dai len phia tren theo huang nhiet tang - Gian de pha cila chat nguyen chat: He me ta day da nhiing bien doi pha cua met chat dieu kien khac v6 nhiet va ap suat, cluing ta xay thing met gian de pha (gian de trang thai) Gian de la de thi P - T, tren lien ket lai cac &tang cong Lang - Hdi, Ran - Lang, Ran - Hdi ma chung ta vita giai thich phia tren va thay ro hon quy tac pha ciia Gibbs Hinh clang gian pha cua CO2 dac trting cho hau het cac chat (hinh 8.4) Gian d6 pha cung cap thong tin v6 trang thai vat lY cua met chat khoang bien dei reng dia ap suat va nhiet do, gem nhcing diem chinh yeu sau: 1 Cdc yang ceta gidn ctd: m6i -yang (Ran, L6ng, 1-16i) Wong Ting vai met pha (trang thai) dia chat Pha ben viing vang cUa no del voi bat kY gia tri nao cila cap thong s6 P - T (he nhi bien) Noi chung, pha ran ben viing nhiet de thap, alp suat cao; pha hoi band nhiet cao, ap suat thap; pha 'Ong ban dieu kien trung gian 2 Cdc du'dng gid'a cac vung: cac &long phan chia viing la nhang dueng cong chuyen pha (da thao luan phia tren) Mei diem tren cac diking chi met cap gia tri P - T, pha cling ton tai can bang (he nh'at bien) Dtiong OA goi la dualig soi (hoac hod 'Ong) Dtiang OB goi la doing nong chay (hoac &Ong dac, hod ran) Dithng OC goi la thieng thang hoa (hoac ke't tu) 3 Diem tdi han (A): dueng Lang - Hoi ke't auk diem tai han A Khi chat (88) G ru a (PK) 73 atm 10 5 -78 -57 Nhi.t d() (T) (°C) 0 31 (T„) Hinh 8.4 Gi3n pha.caa CO2 dac trung cho hau het cac chat:diking Ran - Long nghieng sang ban phai (dO d6c > 0) ap swat tang - bleu thi mat dO pha ran Ion han mat de) pha 'Ong chat lOng cang tang theo Tai nhigt d6 toi han TK, kh6i Wong rieng cua pha lOng va pha hdi bang nhau, bg mat gidi han giita hai pha bign ma D6ng nang trung binh cita cac phan tit tit tren nhi8t ct6 lon dgn mitt hdi khong the ngting dong 16ng cho du ap suat lon bao nhieu Ap suat tticing ling nhi.8t d6 TK goi la ap suat toi han PK (xem them chitong 5, muc 2.1) ci nhiet cao hon TK se ton tai mot dong vat chat sieu hdi, sieu 16ng D6 khong phai la chat 16ng, ciing khong phai hdi binh thitang 4 Diem ba (0): ba &tang cong chuyen pha gap tai goi digm ba, tai cho bigt mot cap gia tri nhat cua hai thong s6 P - T dg ba trang thai cang ton tai can bang: digm ba la bat bign, vi khong thg thay d6i bat kST mot dai Wong nao (T hoac P) ma khong lam mat di can bang d6ng thai cua ca ba pha Diem ba &toe xem la diem kST di, vi tai day, nhit tren hinh 8.4 cho thay: ap suat hdi cua pha ran va pha 16ng bang nhau; CO, vita thang hoa vita kgt tu, vita ming chay vita thing dac, vita s6i vita hod 16ng Tit do, chung ta higu vi da kilo CO, khong thg nong chay digu kin thang: ap suat digm ba cita CO, la 5,1 atm, chat 16ng CO, vi thg khong thg ton tai Khi chat ran CO, duoc dun nong 1,0 atm, no se thang hoa -78°C CO, rat nhanh (xem &tang gay net nam ngang xuat phat tit 1,0 atm tren hinh 8.4) Gia sit, ap suat quygn cita trai dat chang han 5,2 atm, cluing ta se nhin thay cuc da kilo CO, chay 16ng c6c cho dgn hgt -57°C, trtioc no soi va bo'c hdi dgn can He s6 goc cua ba &tang OA, OB, OC dtioc xac dinh b6i phu'dng trinh Clausius - Clapeyron: dP AH cp dT T Av (8-5) 6 day, Aficp 1a nhigt chuyen pha (bign thien Enthalpy dm qua trinh chuygn pha) AV la bign thien thg tich giita hai pha T la nhilet tai digm chuygn pha (89) nhau thi the hoa, tiYc the dang ap mol rieng phan cua chung phai bang nhau: VLA = 11B hoac GA = GB Neu thay deq P va (hoac) T ma can bang van&toe bac) than thi G cua chung phai bien cho: dGA = dGB Van dung phtiong trinh [(6-60), di-acing 6] dG = VdP - SdT, ta có: VdP - SAdT = VBdP - SBdT dP SA S D AS cp hoac = dT VA - VB AV AScp la Entropy chuyen pha cua he V4n dung phttong trinh [(6-50), chtiong 6] truang hop can bang, thi: AH cp L\Scp (He) = -AS (MOi t rnimg) Thay Mei) vao phtiong trinh tren, ta có: dP AH cP dT T AV Vay, phtiong trinh (8-5) da chioc chung minh Ta thay, vdi qua trinh hod hoi (soi) va thang hoa thi pha hdi c6 the tich rat Ion so vdi pha lOng hoac pha ran, do AV c6 the thay bang VHdi: dP AH AHcp X P P AH CP dT TVh„i T R T R T2 hoac: dP AH cp dT P R T2 (8-6) Lay tich phan phtiong trinh (8-6), ta thu dtioc phtiong trinh (8-3) cho biet quan he gilla ap suat hoi va nhiet (da van dung phia tren) Voi qua trinh nong chay, VBA„ va VL6„g khong khac nhieu, phtiong trinh (8-5) dttoc vie't dtioi clang thuan tien cho van dung: ATV — V - Long Rii n \= T (8-7) AP AH CP SO pha cua nuoc khac mot chtit so voi dang chung, phan Lah tinh ch6t (90) Trong he kin, &tang cong ap suat hdi OA chinh la &tang ap suat hdi cUa nu& phu thuOc.nhiet dO hinh 8.2 MOt s6 gia tri cua cac cap P - T xac dinh bang thiic nghiem ghi bang 8.5 136ng 8.5 Ap suat hci nutfic (bac, hoa) cac nhiOt Nhiet dO (°C) Ap suet hdi nit& (mmHg = torr) Nhiet dO (°C) Ap suet hoi woo (mmHg = torr) -10 2,1 60 149 0 4,6 70 234 10 9,2 80 355 20 17,5 90 526 30 31,8 95 634 40 55,3 100 760 50 92,5 101 788 Duang OA di len ket thnc tai A, diem tai han cda nu'ac (6 374°C va 218 atm) va di xu6ng ket tlrac tai 0, la diem ba (a 0,0098°C va 4,58 mmHg = 0,006 atm) Chu 6 he ha, thtfing OA goi ld du'ang cong soi (hoac &fang hoa 'Ong); nhiet dO ghi bang 8.5 'ay la nhiet dO soi tuong iing vdi ap suat ben ngoai (cung la ap suat hdi rut& bong bong hdi hinh long nuac king) Duang OB mo to dieu kien can bang Ran - Lang (Nuac da - NU6c) Khac vdi nhung chat khac, du'ang OB ceta nu'dc có do-c am (nghieng sang ben trai; phtiong trinh (8-7) c6 gia tri am), nghia la ap suat ben ngoai tang tren be mat nu6c c/a, no se n6ng chay d nhiet dO thap hdn DO la kh6i Wong rieng cna nu& da nha hdn nu 6c long, nen ap suat tang tren nu6c da (vi du 0°C) no se chuyen nudc long, tic la chuyen trang thai c6 the tich nha hdn a tang khong gian cua he, lam giam ap suat ngoai tac dOng vao he (Nguyen li Le Chatelier) Theo do, h0 de nong chdy d ap suet cao, nhift ming chdy (hodc (tong cteic) vi the thdp ham (91) 0 HC I Nubc 1 100 NhiOt dij (°C) Hinh 8.5 Gian pha coa nu'dc: clueing Ran - LOng nghieng sang ben trai (d6 d6c < 0) ap suet tang thi mat pha ran (nudc da) nho hcin met pha long (nu'dc) Digm t6i hen (374°C, 218 atm) NUOc DA DiSm ba (0,0098'C, — 0,006 atm) A NU6c LONG ne-u tang ap suet cho pha hoi thi dau tien hoi se chuyen nude da, sau ap suet cao hcin ntia se chuyen nude l6ng Diem ba da nitric nam d ap suet thap (0,006 atm), nen dun n6ng nu& da a ap slat quye'n (1,0 atm) no chuye'n l6ng a 0°C, la diem nOng chciy cua nu'ac da ddu kien thadng (giao diem giiia duffing OB va doffing dirt net nam ngang xual phat tit 1,0 atm) Bai tap van dung: Neu tang Ai) slat atm thi diem (tong dac cua nude lOng (diem nong chay cUa nude da) thay doi the nao? Bi6t: 0°C (T = 273,16°K) Alicp (= AHdd = AH,„.) = 1440 cal/mol, the tich mol cua nude = 18,018 va cua node cid = 19,651 cm3/mol Gidi: De thu dude sit thay dOi dO/atm theo phudng trinh (8-7), trade het chuy'n cac dai Wong ve don vi tilting nhat: AV = Vung - V, 1T1 = (18,018- 19,651) cm3/mol = -1,633 cm3/mol AHdd = 1440 cal/mol x 4,184 x 10' ec/cal \= 6025 x 107 ec/mol = 6025 x 107 dvn.cm/mol Elva cac gia tri vao phudng trinh (8-7) voi Wu phai nhan ca phudng trinh vdi gia tri Wong during 1,013 x 106 dyn/cm2 cho msiii atm: AT 273,16 dO x (-1,633 cm3/mol) - 0,0075 dO/atm AP Vay, tang ap suet atm se lam diem (long dac clia nude khoang 0,0075°, hoac tang ap suit khoang 133 atm se lam diem &Ong dac cua nude khoang 1° Nhu da bie-t„ap suet diem ba efia nude he kin killing có khong la 0,006 atm Khi tang ap suet tit 0,006 atm den atm thi diem &Ong dac thap khoang 0,0075° (xem ligt qua' tren) Diem &Mg dac can thap them 0,0023° bdi sit eó mat cila khong hoa tan nude tai atm Vi va'y, x 1,013 x 106 dyn/cm2.atm AP 6025 x 107 dyn.cm/mol (92) diem deng dac dia niidc d digu kien thueng la thap them 0,0075° + 0,0023° =- 0,0098° so voi diem ba, nghia la tai 0°C 1.4 DO tan - Nhi?ng ygu to anh 'Wang clgn dO tan cua cac chgt 1.4.1 Khcii niem - Dinh nghia - Dung dich that bieu hien vita la hiSn hop co hoc don thuan, vita la hop chat hoa hoc La lion hop vi phan dia dung dich khong xac dinh, c6 the bign doi met giei han reng va tinh chat chUng cila dung dich, to Iran phat hien nhigu tinh chat rieng cita cac cau tit (min vi, mau sac, hod tinh) La hop chat hod hoc vi dung dich c6 tinh deng nhat Mat khac, si hinh dung dich c6 kern theo hieu itng nhiet va bign doi y6 the tich, giOng nhu cac qud trinh hod hoc Mat vay, ve hinh thitc, dung dich chigm vi tri trung gian hon hop va hop chat hod hoc - Dung dich loang hoac dac, bao hoa va qua bao hoa Khi cho chat tan ran vao met dung mOi se xay hai qua trinh Qua trinh tach hat chat tan tit bg mat tigp xuc giiia chat tan va dung mei, goi la qud trinh hoa tan, c6 Vic hoa tan uh, (so' hat chat tan chuyen vao dung mei met don vi thei gian) Cdc hat chat tan dad dung mei c6 the gap lai bg mat cUa chat tan ro'i bi gift lai eau true chung, goi la qua trinh kgt tinh, c6 tic uk, (se' hat chat tan tra lai eau true chung met don vi thei gian) Ban dau, tic hoa tan len hon tic kgt tinh Nhung dung mei da c6 nhigu hat chat tan (n6ng de chat tan dung dich len) thi tic de kgt tinh len dan, tic hoa tan nhe din Co the ton tai tracing hop (xet ding nhiet do): + Ngu u,„ > th„, la dung dich loeing hoac cac, c6 the hoa tan them chat tan (nang Wong Gibbs hoa tan cita he AGht < 0) + Ngu ul,r = uk„ la dung dich bao hat, chat tan khong the hoa tan them duoc nua, dung lion la: met don vi thai gian, c6 bao nhieu hat chat tan chuyen vao dung dich thi ciing CO chiing ay hat tit dung dich tr6 ve cau true ban dau cila chat tan Qua trinh hoa tan dat den trang thai can bang, goi tat la can bang hoa tan - met can bang deng (AGht = 0) (93) thanh nhfing tinh the lon Khi ta khuay, lac dung dich, hoac co dila thug tinh vao binh chlia dung dich, hoac b6 vao dung dich mot hat tinh the chat tan d6ng loai de tao mam tinh the kiwi mao, thi lap tiic chat tan du dung dich qua bao hoa se ket tinh - Dinh nghia d6 tan: D6 tan cila mot chat mot dung moi n6ng d6 dung dich b-do hoa ben yang cila chat nhiet va ap suat nhat dinh Nhu vay, c6 bao nhieu each bieu thi n6ng.,d6 thi c6 by nhieu each bieu thi d6 tan Thong thuang, nguai ta chon cach bleu thi di) tan bang s6 gam chat tan dttoc bao hoa 100g dung moi, hoac s6 mL bao hoa 100mL dung moi dieu kien nhat dinh v6 nhiet d6 va ap suat Nhung chat c6 d6 tan 16n hdn 10g/100g dung moi, du6c goi la nhang chCit de tan; c6 d6 tan tit 1-10-3g/100g dung moi nhang chat kho tan va c6 tan be hdn 10-3g/100g dung moi la nhang chdt thifc to kitting tan Kh6ng c6 chat nao la tuyet doi khong tan Bang 8.6 la vi du v6 d6 tan cila mot so chat dung moi nude va bang 8.7 la d6 tan cila KI cac dung mei khac Bang 8.6 Do tan cOa mot s6 chat nu'dc (g/100g H2O, 20°C) Chgt DO tan Chgt DO tan Glucose 200,0 CaSO4 .0,2 CsCI 186,5 CaCO3 1,3.10-3 LiCI 78,5 AgCI 1,5.10-4 KBr 65,0 AgI 1,7.10' NaCI 36,0 KCI 23,8 H3B03 5,0 Bang 8.7 DO tan co a KI mot s6 dung moi (g/100g dung moi, 20°C) Dung mai DO tan Nu& (H2O) 113,60 (94) 1.4.2 Nhang hie tu'ong tác hat tan - Co bien c6 xay mot chat hoa tan vao mot chat khac: a Cac tieu phan chat tan tach rai b MOt Wong cac tieu phan dung moi tach rai de danh chit; cho cac tieu phan chat tan c Cac tieu phan chat tan va dung moi hoa hop voi tao mot pha dung the (dung dich) Bang 8.8 So sanh n5ng lu'ong cija cac loai lien ke't Oar) ta' va giCra cac phan tt7t Luc lien Wet Mo hinh Tilting tac Nang lu'dng (kJ/mol) Vi du Trong phan ter Ion Cation - Anion 400-4000 NaCI KF Cong hoa tri Kim Ioai - - ; 1' )fl ,._ nhan - Cap e- Cac cation - Electron knot -1g dinh xii 150-1100 75-1000 H-H Cl Fe Zn Cs , - ; ,, GiCra cac phan ter Ion - Wang cut Laing cut - Lu'Ong cut Lien kat hydro Ion - Laing cut cam (trig Lu'Ong cut - Wang cut cam Cmg Khuech tan 0 - :-;- -" 7.3i) -A -}li : .i&,1), -j Dien tich ion - Dien tich lu'ong ctic Dien tich cac luring cut Lien 1(61 phan cut cOa H - {Dien tich luting cut Dien tich ion - May e-phan cut Dien tich luring cac - May e- phan cut Cac may e- phan cac 40-600 5-25 10-40 3-15 2-10 0,05-40 Niff 1-1 H I-CI—CI-I O-H O-H H , H' H' Fe21 0, H-C1 C1-C1 (95) Vay, mat qud trinh boa tan có xay hay khong se phu thuac \TAD d6 manh ttidng dai cua cac lkic lien kgt giiia cac phan tit chAt tan - chAt tan, dung mai - dung mai va chAt tan - dung mai Khi bigt dude cac lite lien kgt, chting to có the dv doin nhiing chAt tan nao se hoA tan dung mai nao - Kign Ur& ye cAu tao chAt chi rang, tat ca cac lite tao lien kgt phan tit va gilta cac phan tit dgu tticing tdc tinh dien cua cac dien tich trai dAu Cdc lute tao lien kgt Oita cac nguyen tit phan tit IA Wong dot manh, vi IA tudng tdc gicia- cdc dien: tich lon (cita hat nhan, ddm may electron, ion Boring hoc am) 4)J nhung khoang each rth6 (ca nguyen tit) Ngti6c lai, cac laic tao lien kgt gitta cac phan tit lajtiong riot ygu, vi cac dien tich nhO (cila cac hiring cuc) nain a khoang cdch lOn (ca phan tit) Bang 8.8 dua sit so sdnh nang Wong cac loai lien kgt phan tit (lien kgt hod hoc thiic thu) va cac loai lien kgt gifta cac phari tit (lien kgt Van der Waals, lien ket hydro) - Cdn chit y sit dung bang 8.8: + Theo Binh luAt Coulomb, hic but (F) giita cac dien tich trdi dA.0 ty le truc tigp \rat dien tich cac ion (q+, q) va qr le nghich binh phticing khoang cach gifia thing (d): q d Nang Wong (E) la hic nhan khoang each (F x d), do nang Wong hitt tY' le true tigp vai cac dien tich va tY' le nghich voi khoang each gifta chting: E q q (8-9) Trong cAu tao chAt, thuAt ngit v6 cac loai he lien ket va theo IA nang ltiong lien kgt, dude sit dung de chi clang he Wong tdc giiIa cac tieu phan + Lien ket ion the hien ca hai kig'u lien kgt phan tii va lien kgt Oita cac phan tit + Cdc thAnh phAn cua hic Van der Waals ke bang can dtt60.hieu theo nghia rang, g6m he lien kgt gala cac Wang civic: vinh citu - vinh citu, vinh ciiu - cam ling, khuech tan khugch tan hoc gifia ion - vinh ciiu, ion - cam ling; lien IC& hydro (xem hiring tti nlitt hic gifia cac hiring cvc vinh ciiu - vinh cat hoAc ion - vinh ciiu) va ke ca hic lien ligt gifia cac ion (96) Lu'c lien ket ion - lu'Ong cvc c6 vai tro chir yeu qua tri.n.h hoa tan cac hop chgt ion nuoc Luc lon hon hic but gilia cac ion nen c6 the pha va caU trac tinh the ion ciia muei va hoa tan no Khi met ion dUoc tach ra„cac phan tip rliteic barn quanh bang clic trai dgu tao ion hydrat D6 la hien tu'dng hydrat hod hoa tan (hinh 8.6) (neu dung mei khac nuoc goi la hien twang solvat hod) VO cac phan tii nuoc bao quanh m6i ion khong c6 cgu triic c6 dinh vi chUng tvcing tac voi cac phan tit mioc khac cua ca khei dung mei dung dich qua cac cdu ne'i hydro Tuy nhien, c6 nhfing hop chgt hydrat kha ben, chgt tan tach khOi dung dich, cac phan tii rut& van nam tinh the chdt tan, vi du cac mu6i hydrat CuSO4.5H20 ; Na2B407.10H20 ; MgSO4.7H20 ; Na2SO4•10H20 v.v Hinh 8.6 Qua trinh hoa tan NaCI nuttc va sV hinh cac ion hydrat Na+ (aq) va (aq) Lien ket hydro la loai luc da'c biet Wang citc - hldng cue chiu trach nhiem ve kha nang cim nu& hoa tan nhieu hop chgt hiiu co phan tii lon chita 0, N, F nhu cac alcol, cac clueing, cac amin, cac chdt c6 gan fibvao khung phan Lu'c lien ket ion - lufing cvc cam zing hien tro giUp cho hoa tan cac hop chgt ion (cac hoac cac dung mei it phan cuc Luc cung c6 the dung giai thich ski tao ion phitc iodid hoa tan iod dung dich kali iodid: 12 + -> K13 Lt.& lien ket lu'ang cue - lu'ang cu'c cam zing la loai fuc yeu, vi citc cam ling (97) Ltfc khuech tan luon xuat hien moi thai di6m, giup cho sit hoa tan cila moi chat moi dung moi NO tra lilt lien k6t chinh yeu hoa tan giiia cac chat khong phan clic vao VI du, lilt lam cho dau mO tr6 h6n hop d6ng nhgt (dung dich cua cac loai hydro carbon phiic tap) - Sit hoa tan cac chat ran, chat lOng: Kinh nghiem pha the hod hoc da rut quy ta'c don gian: gang nhau thi hod tan vao Nod each khac theo ban chat cau tao, cac chat cling kieu lilt lien ke't gifiia cac phan tii thi có th6 hoa tan vao Bai vi, ne-u cac lvc lien ke't giiia cac phan to chat tan - chat tan gi6ng nhu hoc gan nhii lift lien ket gifita cac phan tit dung moi - dung moi thi chimg d6 clang thay the nhau, "lan" vao de hinh dung dich (bie'n c6 c) ma khong can vitot qua at cach biet cua hang rao nang Wong (d6 thvc hien bie'n c6 a va b da neu phan dau de muc nay) NU6c hoa tan cac mu6i, vi lilt lien ke't ion - tang cvc Oita nu& va cac ion la rat hiring d6ng vdi hic lien ke't manh Oita cac ion tinh the mu6i, do chUng có th" thay the Cling chinh cac muoi nhung lai khong tan dung moi hexan (C61114), vi lilt lien ke't ion - Wang cite cam ling giiia cac ion va dung moi khong phan cvc la ye-u, khong the thay the hic lien ke't ion mu6i Thong tit, dau and kh6ng tan nude vi cac hic lien ket ludng clic - Wang clic cam ling giiia nitric - dau and khong the thay the lilt lien ket hydro giiia cac phan tit nude Tuy nhien, dau ma lai hoa tan hexan vi 1Vc khuech tan chat thay the tot cho lilt khuech tan chat Trong cac dung moi khdc nhau, d6 hoa tan cila cac chat cling phu thu6c vao hic lien ke't gala nhfing phan cua phan tit chat tan vdi dung moi Vi du, xet d6 tan oda mot day alcol hai dung moi la nitric va hexan Hai dung moi co d6 phan clic khac xa (momen ludng cVc I.1.20 = 1,84 D va = 0) Chat tan la alcol chila mot nhom hydroxyl (-OH) lien ke't vdi chddi hydrocarbon, tong thitc chung CH3(CH2)"OH, vdi n = den (bang 8.9) (98) nang phan re cac lien lie't hydro manh nudc de chen Lan, fan vao dung moi (nuoc) Va nhii da thay a bang 8.9, dO hoa tan nuoc giam ti alcol C den C Bang 8.9 Dd hoa tan coa day alcol nu'dc va hexan Alcol Trong ntroc 20°C (mo1/100g H2O) Trong hexan 20°C (mo1/100g C61-114) CH3OH (methanol) oo 0,12 CH3CH2OH (ethanol) CH3CH2CH2OH (propanol) 7", oc CH3CH2CH2CH2OH (butanol) 0,11 09 CH3CH2CH2CH2CH2OH (pentanol) 0,030 00 CH3CH2CH2CH2CH2CH2OH (hexanol) 0,0058 09 Tinh the se nguoc lai, ne-u dung moi la hexan day, luc ttidng tac cd ban gifia chat tan - dung moi la cac luc khuech tan Luc tddng tac yeti gifia nhom -OH cila methanol (CH:30H) va hexan khong the thay the cho luc toting tac manh gifia cac phan tU CH3OH, vi the d6 tan cUa methanol hexan la Wong d6i nhO Trong nhang alcol ldn hon, cac laic khuech tan tra nen quan hdn, chUng có the thay the cho cac 11.1c khuech tan hexan, do cac alcol tif C trei di da hoa tan vo han dung moi - Bai tap van dung: + Dung moi nao hoa tan nhi6u hon d6i voi mot chat tan da cho? Vi sao? a NaC1 methanol (CH3OH) hay propanol (CH3CH2CH2OH)? b Ethylenglycol (HOCH2CH2OH) ruidc hay hexan (CH3CH,CH2CH2CH2CH3)? c Diethyl ether (CH3CH2OCH2C1-1:3) ethanol (CH3CH2OH) hay nuoc? + Chat tan nao hoa tan nhigu hon vao mot dung moi da cho? Vi sao? d 1,4-butandiol (HOCH2CH2CH2CH2OH) hay butanol (CH3CH2CH2CH2OH) nuoc? (99) Gicii: a Methanol NaC1 la hdp chat ion N6 hoa tan dung moi nh6 laic lien ket ion - ludng cue Luring cuc methanol manh hdn chuiii hydrocarbon ngAn hdn so WA' propanol b NU6c Ethylen glycol c6 hai nhom -OH nen cac phan tii cita no -Wang tac vdi qua lien kgt hydro manh, giOng nhu lien ket hydro ntioc Vay, no tan nhigu nude hdn la hexan vi ftexan chi On tai Ric khuech tan c Ethanol Cac phan tii diethyl ether tudng tac vdi qua hic lien ket hiring cuic - ludng chic va laic khugch tan; chung c6 the tao lien ket hydro vdi nude va ethanol Nhuing ether se tan nhigu hon ethanol, vi dung moi visa tao dtioc lien ket hydro (ludng cuc - ludng cuic), \Fifa tao hic khuech tan voi chat tan Vi vay, chting chuyen cho va lan vao tot hdn la trong nude chi c6 luc lien ket hydro d 1,4-butadiol tan tot hdn nude vi c6 the tao dude nhigu hdn lien kgt hydro e Chloroform tan nhigu hdn nu6c vi tao dtioc cac luc lien ket luring cue - Wang cuc Trong phan tii cua nhigu hop chat him cd c6 ca phan phan ctic va phan khong phan cuc, ma su nOt trOi cita phan nao se guy& dinh hoa tan cita chat cac dung moi khac Cac phan tii xa phOng la muoi cua hydroxyd kim loai voi acid beo dai 15 den 19 carbon, vi du natri stearat CH3(CH2),6C00-Na+ Duoi hydratcarbon khong phan cuc tao luc lien kgt khuech tan v6i dau and nen tan vao dau ma, dau ion phan clic (COONa+) tan nti6c luc lien ket ion -ludng cuc va lien kgt hydro Su xao trOn tao cac hat dau and nh6 xiu dude bao quanh bai cac phan tii xa phOng va dOng nti6c se cuOn di, lam sach cac vet dau and barn tren de vat [cation cita phan tii xa phong anh huang den tinh chat cula no Xa phong Li+ cling, diem nong chay cao duck sii dung lam dau boi trdn cac dOng cd Xa phOng Na4" thong dung vi hoa tan -at nude Xa phong c6 diem nong chay th'ap ditn.g lam cac loaf xa phOng lOng xa phong Ca" khong tan nude da giai thIch vi kho lam sach de vat bang nude cling (eh-Cm nhigu Ca") sii dung xa phong thong thuang] (100) [SU thieu hi5u biet quy tac hoa tan giita cac chat cang gop phan vao sti lay lan ciia AIDS Ng-la:1i ta sii dung cac chat boi tron len bao cao su hoac cac ma.ng ngan vdi muc dich giam ma sat va gin cho bao hoac mang khong bi rach Thiic ra, cac chat boi trcin (la dau, kem xoa) khong phan clic có th5 hoa tan cao su ding la nhang chat khong phan chic Ngay tit phut boi troll dau tien da tao cac 16 thing tren cao su ma mat thuang khong th5 nhin thay, nhting cac 16 có the de cho HIV va tinh dich di qua Hall qua la AIDS lan truy6n hoac có thai ngoai y muon] - Su hoa tan cac khi: Cac có di5m soi thap vi luc Wong tac giiia cac phan tit nit& Mat khac, cac d5u hoa tan rat it nueic vdi ding 1ST do: 11.1c lien k5t gifita cac phan tai chat tan (khi) - dung moi (midc) rat y5u Thuc t6 có moi tracing quan giiia nhi5t soi cua va tan dia no nuoc (bang 8.10) Ltfc tuong tac nhO den miic cho phep thong ta c14 doan tan ciia dung moi thi chi can xet cac 111c lien k5t chat tan - dung moi va dung moi - dung moi, chit khong can xet he gicia chat tan - chat tan Bang 8.10 TYOng quan gitia nhiOt d6 soi va di) tan caa mot s6 nutic Khi DO tan (M) (6 25°C va atm) NhiOt dO sal (°C) He 4,2.10-4 -271,9 Ne 6,6.10-4 -246,1 N2 10,4.10-4 -195,8 CO 15,6.10-4 -191,6 02 21,8.10-4 -182,9 NO 32,7.10-4 -151,8 Wit luring nhO 02 hoa tan ntidc (0,64 mL 02/100 ml H2O atm va 25°C) la rat thi5t yen cho su song cua ca va cac d5rig vat thq sinh khac mot vai trUang hop, d5 tan cila có ye ldn, nhung thiic la có phan ling cO.a vdi dung moi hoac vdi mot phan khac co mat moi truang Vi du, CO2 có d5 tan nuoc 10n (- 81 mL CO2/100 mL H2O d atm va 25°C) vi ton tai phan ling lam tang d5 boa tan: CO2 (k) + H2O (1) H+ (aq) + HCO3- (aq) (101) * Tom tat ve dO tan: dung dich la nhiing h8n hop d'Ong the chita chat tan hoa tan mot dung moi nha tac dung dia cac luc phan tit D6 tan cim mot chat la Wong tea da chat co the hoa tan mot Wong dung moi xac dinh, du oc bieu thi bang cac loai n8ng d6 cho dung dich dat trang thai bao hoa di6u kien nhat dinh Cac loaf 11,ic phan tit dung dich la ttidng diing (gi6ng) vdi cac loai phan tit moi chat nguyen chat tilt& hic hoa tan Neu luc phan tit dung moi va chat tan giting nhau, sit hoa tan luon xay Luc ion - luang citc du kha nang de hoa tan cac hop chat ion vao nu6c M8i ion nuoc duoc bao quanh lop vO hydrat (vO tao 136i cac phan tit nuoc htit cac ion bang cuc trai dau) D6 tan cila cac phan tit hitu co nueic phu thu6c vao quy m6 cua phan phan cuc va phan khong phan ctic Cac xa phong, mot s6 thu6c khong sinh boat dOng theo cd the tac dung cua hai d6 phan cuc phan tit cim thong D6 tan cilia cac nitric rat nhO vi he lien ket gift cac phan tit chat tan - dung moi rat yeu [nhung nhO rang, cac hoa tan vo han vao Chung cung hoa tan chat ran nha chie-m gilt nhung phan khong gian tinh the qua cac luc lien ket] Khi van dung quy tac Wong thing "giong thi hoa tan vao nhau" cho d6 tan, ta can xem xet day &I cac tuong tac ve hoa hoc, dien va eau true phan tit gifia chat tan va dung moi 1.4.3 Anh htthng ceta nhiet clo ud ap suet den dO tan Dinh lui:tt phtin bo: Dinh lust Henry D6ng luc cila qua trinh hoa tan la nang Wong tut Gibbs: AGht = Alfht - T ASht (8-10) 6 day, AHh, la Wen thien Enthalpy va AS,„ la bien thien Entropy cila qua trinh hoa tan ma bieu thitc ciia cluing dii6c vi6t: OH,„ = AH„ + AHhydrat (hoac solvat) (8-11) ASht = AS, + A Shvdrat (hoc solvat) 4 (8-12) Met: bien thien Entropy chuyen pha cUa chat tan AShvdrat (hodc solvat) Dila yap cac pinking trinh nhiet thing hoc tren, ta c6 the xet su thay d84 d6 tan cila cac chat theo nhiet d6 va ap suat Mat khac, can Wu ST 6 nhang dung dich bao hoa ton tai cac can bang: + Giita chat tan dit thlta va chat tan cid dung dich bao hoa tai nhiet d6 nhat dinh: Chat tan (du thita r,l,k) Chat tan (8-13) (trong dung dich bao hoa) (102) + Giiia nhiet hoa tan can hap thu va si tao dung dich: ChSt tan + Dung mOi + Nhi4 Dung dich (bad hoa) + Gina nhiet hoa tan toa va sti tao dung dich: Chgt tan + Dung mOi Dung dich + Nhie't (8-15) (bao hoa) Diia vao nhang pinking trinh tren day, to c6 the xem xet d6 tan phu thu6c cac dieu kien cho nhung truang hop du the DO tan czla chat ran chat 16ng R /L): + Vi AH„ tIntang lon, dac biet la cac hop chat ion c6 n.ang Wong mang lUdi tinh the (AHmi) rat lon, nang Wong giai phong hydrat hod (hoac solvat hod) khong du ba dap, nen AHht > Khi tang nhiet d6, theo pinking trinh (8-14), can bang chuyen dich sang phai Thu'c to thing la da so cac chdt rein có coo tan tang theo nhiet ctO (hinh 8.7) Dieu clang de clang thay du oc qua bien thien nang luong tu Gibbs (AG11 ): theo phudng trinh (8-11), AS, >> (vi chat ran tinh the di trat to rat cao chuyen chat tan 116'n don dung dich), AShvdta, (hoac solvat) < nhting kh6ng clang ke (vi trat tki hydrat hod hoac solvat dda lai thap va khong on dinh), nen ASht > (luon luon) Neu tang nhiet d6 (T), s6 hang (-T.ASh) cang am hdn va vuot qua AHht > 0, clan deia AGht cang am hdn, d6 tan caa chat ran vi the cang ldn + Nglioc lai, nhang chat ran khac c6 nang Wong hydrat hod (hoac solvat hod) giai phong ion, AH hydrat tho4c solvat) << 0, va ne-u nang Wong mang (AH,„) caa chat tan lai nh6, thi AHht < 0, qua trinh hoa tan phat nhiet Theo phu ong trinh (8-15), tang nhiet d6, can bang bi day lai sang trai, nghia la coo tan ceta chdt gidm tang nhi'Ot dO VI du, dieu xay hoa tan vao nude cac chat kiem, Na2SO4, Ce2(SO4)3, nhieu muoi cUa lithi, magnesi, nhom Ta cang tim thay tticing quan nghich giaa d6 tan va nhiet d6 (T): vi qua trinh hydrat hod (hoac solvat hod) manh me nen AShydrat (hoac solvat) << 0, d'an den ASht < Neu tang T, so" hang (-T.ASht) cang diking hcin va vudt qua AHht < 0, dan den AGht, cal-1g &tong hdn, qua trinh hoa tan bi day lai, d'6 tan vi the giam xueng (103) KNO -r - - KI 200 1 1 i 1801- - CaCl2 _ KBr 4- —I- ; KCI —1 Na,S0, NaCI K SO 20 DO ho a tan g /1 00g nt Idc 40' 100 60 0 10 20 30 40 50 60 70 80 90 100 NhiOt dQ Hinh 8.7 Su' phy thu6c giUa d6 hoa tan caa mot s6 mu6i nu'dc vao nhiet d6 Tren hinh 8.7, nhang dttdng cong tan nao hudng manh len tren thi chi:mg to tang nhiet do, tan ciia cac chat tang len manh Do tan cila NaC1 bign d6i it theo nhiet de, nen &tang cong tan cila no gan nhii nam ngang DUOng cong tan cila CaC12 va Na2SO4 bi gay tai cac cuc dai la -Wong ring voi tan dm cac clang tinh the muei khan va mu6i hydrat tai cac nhiet Vi du, tan cUa Na2SO4.10H20 duoi 32°C tang nhanh theo nhiet 0, vi qua trinh hoa tan hap thu nhiet nhiet de cao hon 32°C, pha ran na.m can bang voi dung dich bao hoa la muol khan Na2SO4 ma su boa tan no la qua trinh toa nhiet, nen de tan giam nhigt tang Data vao dtiang cong tan ngtiai ta có the tinh chg cac chat ran bang cach kgt tinh lai Cu the la: tao nhang dung dich bao hoa ci nhiet cao chlia nhfing Wong mu6i lon, roi sau lam lanh de có cac dung dich qua bao hoa d nhiet th'ap Khi met Wong mu6i "du" tinh khigt se kgt tinh, lai tap chat khong dat duoc ang bao hoa van nam lai dung dich De có mu6i that tinh khigt, nguai ta kgt tinh lai vai lan nhu vay Cac muel có de tan bign de'i nhigu theo nhiet dgu có the tinh chg bang cach [DO tan cila met chat thuang lon nhat dung mei nguyen chat va thuong giam xugng dung dich da có mat cac chat khac Vi du, 20°C, de (104) hoa NaC1 la 0,3 L(C12)/L (dung dich NaC1 baO hoa) Vdy, tan dd.- giam 10 Ian Nguyen nhan la luc ion cila dung dich len dd lam giam de tan cila cac chat] Khi boa tan chat ran chat long, the tich cii.a he Eden doi khong clang ke Vi vay, tan cUa cac chat ran thtic to khong phu thuec vao ap suat - DO tan cila chat fOng chat liing (he L/L): + Met se chat fOng tan khong gioi han vao nhau, nhu cac alcol phan tii nhO ntidc Nguyen nhan co sti Wong deng ve lve lien ket chat tan, dung mei va dung dich + Met se' chat king khac dtioc coi la thiic t6 khong tren Fan voi nhau, vi cac hic lien ket chting khac xa nhau, vi du rut& - dau hoa, nuoc - benzen, nudc - thuY ngdn + Nhieu chat long khac chi hoa tan met phan vao nhau, nhu ether ethylic/ nuoc (khi lac ether voi mioc roi de phan lop thi lop tren la dung dich bac) hoa cua nuoc ether, lop du& la ether bao hoa nuec) Trong h'au het cac trUang hop, hai chat lOng hoa tan giei han vao nhau, neu tang nhiet de thi tan cua chung tang cho den dat dtioc nhiet mad hai chat lOng tan vao theo bat kY tY' le nao Nhi-et dO, ma tai hai chat lOng tan uO han veto got let nhift dO tdi han Vi du, duoi 66,4°C phenol chi tan met phan nude va nude tan met phan phenol Nining bat dau tif 66,4°C thi phenol va nuec tan khong gidi han vao Nhiet 66,4°C la nhiet tdi han cila he phenol - ntidc Thong -U.!, he anilin - nuec có nhiet tdi han la 167°C Do tan cila chit lOng tang theo nhiet cling dvoc giai thich Wong tu nlui d truing hop tan cila he R/L Tuy nhien, Alict ciia chat tan lOng nhO (it &king) va L\Hhydrat (hoac solvat) thuang am nhigu hdn nen AHh„ thuang < 0, ASh„ thuang > 0, theo AGht am nhieu hon nhiet de tang Tai nhiet tdi han, AGht << 0, tan cua he L/L vi the tra nen vo han Cling nhu he R/L, ski hoa tan vao giiia cac chat lOng it phu thuec vao ap suit Do tan ciia cluing chi tang len ro ret d ap suit hang nghin atmotphe I - Dinh ludt phan b6: Neu met chat X co nang tan hai dung mei khong tren ran L1 va L2, thi X se duoc phan b'6 vao ca hai dung mei cho 6'7 le cac n6ng cila (105) CX/L, (8-16) CX/L Cx/Li la ang d8 chat X dung moi L1 Cx/L2 la ang di) chat X dung moi L2 F goi la he s6 phan b6, mot hang sod nhiet d8 nhat dinh Vi du, iod có the tan ca hai dung moi khong trOn fan la chloroform (HCC13) va nudc vdi he s6 phan b6: C12 / clorotorm C1 / nit& He s6 khong phu thu8c vao Wong chung cua iod hoa tan, nghia la du hiring iod ban dau nitric (h0c chloroform) la bao nhieu, n1rUng sau lac hai dung moi vdi va sau de yen cho chting tach hai thi n6ng I, chloroform luon luon 130 lan ldn hon so vdi neng cila no nude Nhu vay, nho chloroform nguOi ta có the chi& (tach ra) rat& hau het iod hoa tan do, neu qua trinh chiet duoc lap lai nhieu lan TuST theo he s6 phan b6 cila chat tan he hai chat lOng khong trOn Ian ma nguai ta chon dung moi chi& cho thich hop Nhung dung moi thuang dfing qua trinh chi& dau hoa, xang, benzen, carbon disulfid (CS2), aceton, carbon tetraclorid (CC14), rtiou ethylic, ruou methylic, chloroform Sau chiet, cac dung moi duoc thu hoi de tai sit dung - DO tan caa cac chat chat- rdng (He K I L): + Vi Afict = (chat tan la nen khong can tieu ton nang Wong de tach cac tieu phan) va AH —hydrat (hoac solvat) < 0, nen AHht < (luon luon) Vay, szc hod tan chdt chat lOng qua trinh tod nhiet Theo nguyen 1ST chuyen dich can bang ap dung cho phuong trinh (8-15) thi cho tan caa chat cl-ju gidm nhift ctO tang vet ngu'ac lai [net' de c6c int& lanh 6 ch8 gm se thay cac bot barn vao ben c6c, la khong tan nuoc lanh thoat nhiet tang Dun s8i toan bo khong da tan nuoc &toe giai phong] Ta cling de clang giai thich duoc quy luat d8 tan cila mot cach ban chat hdn qua nang Wong ti.1 Gibbs: Affe, ro rang bang 0, chi AHhydrat (hoac solvat) < nhungkhong lon (ve gia tri tuyet deci) cac liic lien ket chat tan -dung moi deu yeu, dan den AHht < nhung cling khong dang ke Mat khac, ASht << (luon luon) vi ASc, va AHh—hydrat (hoac solvat) ydrat d6u am (chat (106) tri cila.iht va ASht vao phitong trinh (8-10), ta nhan thay AGht chi < nhiet d6 T nhe, va T cang nhe AGht cang am hdn, nghia la tan dm chat 16ng tS7le nghich vdi nhiet [Co vai (vi du cac tro) hoa tan dung mei hitu cd lai kern theo hap thu nhiet, nghia tan ciia chi ng tang nhiet tang Sti bat thiteng gay nhung hieu Ung dac biet (khong neu day) lam cho ASI„ vita du > 0, nen T tang, AGht tra nen am hdn, tan cUa vi the lon hon] Dinh luat Henry (1803): Gia thiet trong.be pitteng - xilanh (dat thang ditng vei pitteng nam phia tren) chita dung dich bao hoa met chat met dung mei 'Ong a nhiet de xac dinh Tren mat dung dich bao hoa la chat a ap suat P Trong he kin nInt the se thiet lap met can bang, nghia la s6 phan tit di vao dung dich va tach khidung dich met don vi thei gian bang nhau: Khi + Dung mOi Dung dich (8-17) Neu day pitteng a nen khi, the tich giam, ap suat cila no tren mat dung dich tang len Theo nguyen 1ST chuyen dich can bang cila Le Chatelier, can bang (8-17) se chuyen sang phai de giam ap suat, nghia la hoa tan nhieu hdn vao dung dich Met can bang mei ditoc thiet lap vei tan cila len hon Tit do, Henry TA phat bieu dinh luat: DO tan ciia mot (Sk) ty le thu(In vdi cip suat rieng phein cita no (Pk) tren mat dung dich: Sk = kH X Pk (8-18) O day, kH la hang s6 Henry rieng cho m6i cap - dung mei nhiet xac dinh Neu tan Sk tinh theo n6ng mol/L va Pk theo atm thi this nguyen cua kH la mol/L.atm Can Wu ST met he qua quan cua dinh luat Henry Gia thiet a T = const, itng vei ap suat P1, c6 the tich V1 dia hoa tan met the tich xac dinh dia dung mei, tticing ling vei s6 mol hoa tan la n1 = P1V1/RT Khi tang ap suat len n lan, gia sit ap suat dat P2 Ira the tich hoa tan la V2, thi s6 mol hoa tan bang n2 = P2V2/RT Theo dinh luat Henry, ap suat tang n Pan, n6ng de theo khei Wong cUa (hay s6 mol hoa tan) cling phai tang n lan Tit ta c6 the viet cac bieu thitc sau: n2 = n x n1 = P2V2/RT = n x (P,Vi/RT) (107) Nhu vay, the tich hoa tan sau tang ap suet len n len van la V1, giting nhu truck tang hp suet He qua la, the' tich cda chat tan mot the' tich xac Binh cda chat 16ng nhiet c1-0 khong ddi khong phu thu0c- veto ap suet rieng phdn cda no Chinh vi vay, ngi.thi ta thuang bieu thi do-tan cue chat bang s6 mL 100 mL dung moi, chic khong dung s6 gam 100g dung moi nhu thong le d6i veil chat ran va chat Bang 8.11 ghi dO tan cila mot s6 chat nit& d 0°C va 20°C Bang 8.11 DO tan (mL/100 mL H2O) caa cac kW 0°C, 20°C ve ap suet atm Ch'it DO tan Chat DO tan 6 0°C 20°C d 0°C O 20°C Hydro 2,15 1,8 Carbon dioxyd 361 240 Oxy 4,90 3,1 Clor 461 236 NitO 2,35 1,5 Metan • 5,5 3,3 - Bai tap van dung: Trong mot nha may san xuat d6 u6ng có gas, ngtfai ta nap CO2 \Tao cac chaff nu& ngot duoi ap suet rieng phan cua CO2 bang 4atm Tinh dO tan ciia CO2 die'u kien nay, biet hang s6 Henry dia CO2 nu& a 25°C la kH = 3.102 mol/L.atm Gidi: Ap dung phuong trinh (8-18) vesi Pco, = atm va kH da cho, ta co: SCO2 = (3 x 102 mol/L.atm) x atm = 0,1 mol/L 2 CAC MINH CHAT CUA DUNG DICH CHI-TA CHAT TAN KHONG DIEN LY VA KHONG BAY HOI 2.1 WO ap suet hdi cila dung dich Dinh luat Raoult (108) Hinh 8.8 Anh twang cua chat tan den ap suat hal cua dung dich A - Can bang duoc thiet 10p gilia dung moi nguyen chat (o) va áp suat hot cua no khi s6 phan to bay hot bang s6 phan tit ngu'ng dong mot don vi thdi gian B - Khi CO mat chat tan (a) khOng bay hot, be mat bay hot cua dung moi tren dung (itch thu nha 10, s6 phan CO bay hot cang nhLt ngu'ng dong it hon mot don vi thdi gian Trang that can bang L6ngR="•.- Hai cua dung dich xay raa áp suat hoi th5p hon so voi dung moi nguyen chat Vg tlidng quan dinh luting, Raoult phat bigu dinh luat 1: Ap suat hdi cua dung moi tren dung dich bang neing dO phan mol cua dung moi dung dich (luon luon < 1) nhan v6i ap suat hoi cii.a dung moi nguyen chat [lieu fly& cua dinh luat duoc vigt: Pad = Xdrn X P dm (8-19) o day, Pdd 1a ap suat hoi (bao hoa) cua dung moi tren dung dich P dm la alp suat hoi (bao hoa) cua dung moi nguyen chat Xdm la ngng dO phan mol am dung moi dung dich Vi X,„ + Xdm = (X„ la ang dO phan mol cua chat tan), nen co thg bign d6i piniong trinh (8-19) mot s6 phuong trinh he qua: Pad = (1 - X,) x P dm (8-20) AP = P m Pdd = X, x P dm (8-21) dm Pdd AP (8-22) dm dm Voi AP la dO ap suat hoi cua dung dich AP la tildng d6i ap suat hoi cua dung dich so voi ap suat hoi cua P(ci'm (109) - Bai tap van dung 1: Tinh d6 dp suat hdi AP cita dung dich 10mL glycerol (C3H803) hoa tan 500mL milk a 50°C Tai nhiet d6 nay, dp suat hdi bao hoa cua rni6c nguyen chat 92,5 mmHg va kh6i Wong rieng cilia no 1a 0,988 g/mL; kh6i Wong rieng ciza glycerol 1,26 g/mL Gidi: So mol glycerol = 10 mL x 1,26g x lmol = 0,137 mol lmL 92,09g 0,988g x lmol lmL 18,02g 0,137 mol Xet (glycerol) — = 0,00498 0,137mol + 27,4mol Tinh AP theo pinking trinh (8-21): AP = Xct (glycerol) X P dm (H20) — (AP nh6 la hop lY vi n6ng phan mol cila chat tan rat be) - Bai tap van dung 2: Tinh d6 dp suat hdi dia dung dich hoa tan 2,00g aspirin (M = 180,16 g/mol) 50g methanol (CH3OH = 32) a 21,2°C Methanol nguyen chat d nhiet d6 có ap suat hdi bao hoa la 101 mmHg Gidi: AP = Xct (aspirin) X P dm (methanol) 2,00 g 180,16 g/mol 2,00 g 50,0 g 180,16 g/mol 32,0 g/mol = 0,713 mmHg x 101 mmHg 2.2 Do tang nhit soi cila dung dich Dinh 1u4t Raoult MO chat lOng bdt 16, se soi d nhiet coo ma ap suat ho'i bdo hod ceict no bng ap suat ben ngoeti (11Ic ca kh6i chat long se b6c hdi, khong rieng tren be mat) Vi dung dich (chlia chat tan khong bay hdi) có dp suat hdi bao hoa luOn luon nh6 hon ap suat hdi bao hoa cila dung moi nguyen chat, nen nhiet d6 ma dung m6i nguyen chat soi thi dung dich chtia soi Tren gian d6 pha d hinh 8.9 cho thay, &tang cong dp suat hdi dm dung dich nam dvoi &fang cong dp suat hdi cila dung moi nguyen chat nen dung S6 mol H20 = 500 mL x 27,4 mol (110) Dung dich Can bang \ nuoc long - nu6c dzi i I RAN At„ AP thl 760 eu E (7) 4,58 Di6m ba I A, LONG HOI At dich se soi nhiet d6 cao hon Dung dich cang dac, d6 ap suat hdi AP cang Ion, nhiet d6 soi cang cao Can bang dung dich - nu6c da Nu& tinh khi6t t", 0" 0,0098" 100" t", NHIET ISO ("C) Hinh 8.9 NhiOt dO clOng dec va nhigt d0' soi coa dung moi tinh khigt (nuOc) va cu'a dung dich (gie'n khOng theo tji re) - Dinh it* Raoult thik lAp quan he dinh Wong gicia ang d6 va d6 tang nhiet d6 soi ciia dung dich qua phticing trinh: Ats = Ks x m (8-23) day, Ats =t :: (dd) t (dm) goi IA d6 tang nhiet soi cUa dung dich vdi t( (dd) IA nhiet d6 bat dau soi cila dung dich es) (d m) nhiet soi cila dung moi nguyen chat m ming d6 molan dia chat tan dung dich Ks hang so soi cila dung moi Vi m = thl Ats = Ks nen ngticii to goi Ks la d6 tang nhiet d6 soi molan Bang 8.12 cho biet nhiet d6 soi vb Ks do'i voi mot s6 dung med (111) Bing 8.12 NhiOt soi, nhiOt deing dac, hang s6 soi (K s) va hang s6 clOng clOc (<d) cu'a mot s6 dung mai atm (K s, K d khOng phu thue)c vao ban chat ca a chat tan, chi phy thuOc vao ban chat cua dung miii) Dung mei Nhit soi (°C) Ks (°C/m) Nhiet dO dong dac (0C) Kd (°C/m) Nutic 100,00 0,512 0,00 1,86 Acid acetic 118,0 2,93 16,6 3,90 Aceton 56,0 1,71 -94,8 2,40 Benzen 80,1 2,53 5,20 5,12 Cloroform 61,7 3,63 -63,5 4,70 Ethyl ether 34,6 2,02 -116,3 1,79 Phenol 181,4 3,56 42,0 7,27 Nhiet soi cila dung dich &foe tinh la nhiet de bAt d'au soi (khi xuat hien bot hdi dau tien) Qua trinh soi cila dung dich clula chat tan khong bay hdi se lam Wong dung mei dung dich giam dam bay hdi, n'Ong dung dich tang clan, do nhiet soi cang tang dan (khac voi dung mei nguyen chat có nhiet soi c6 dinh) Nhiet soi ciia dung dich se hAng dinh dung dich dat trang thai bao hoa, vi cung voi sti bay hdi cilia dung mei, chat tan se ke't tinh -Wong ling Tuy nhien, nling dung dich Ric rat lon, khac nhi'eu ved dung dich loang, nen phtiong trinh Raoult khong Wong thich 2.3 DO nhi'Ot dOng dac cita dung dich Dinh 1114 Raoult - Trong die'u kien thulang, met chat nguyen chat se deng dac hoac &mg chay ii nhiet ma tai can bang giiia pha rAn va pha 'Ong c3 atm difoc thigt lap Hinh 8.9 cho thay, nitric tinh khigt deng dac tai 0°C d ap suat quyen 760 mmHg (1 atm) Tai diem ba cua nitric tinh khi6t t1.1 bay hdi than khong (he kin); can bang cua ba pha rAn - bing - hdi dude hinh tai ap suat 4,58 mmHg va nhiet 0,0098°C Nhiet deng dac cua int& d diem ba khong trang voi nhiet (long dac cua nude ap suat quye'n, nhting dung vdi ap suat hdi rieng phan cua no De nhiet (long dac (Atd) cila dung dich dtiOc chi tren hinh 8.9 Chu Sr rang, &tang cong can bang RAn Long cOa dung dich nam ben trai chi6ng cong cua dung mei nguyen chat, nghia la dung dich luon &rig dAc d nhiet thap lion dung mei nguyen chat Dieu có the giai thich bang nguyen 1ST chuyen dich can Wang cila Le Chatelier Can bang gifia (112) (H20), (H20)1 AHcp > Nhu vay, qua trinh chuyen pha tii Ran Long luon thu nhiet Hoa tan mot Wong chat nao d6 vao nuOc long, dung dich duoc tao thanh, n6ng cac phan tii niidc pha Fang giam xu6ng, can bang chuyen dich sang phai lam tang no - tic la nuoc da ming chay He tu thu nhiet va can bang moi duoc thiet lap ci nhiet dO thap hon Ta ciing c6 the hieu nguyen nhan o cap dO phan tit Do cac tieu phan chat tan c6 mat dung dich can tra nen s6 tieu phan dung moi tack hoac di vao phin (tong dac cua chung giam xu6ng, dQng nang cac phan ti dung moi va theo d6 nang Wong cUa he (dung dich) cao VI vay, de dung moi dung dich dong dac duoc, nhiet ciia dung dich phai thap - Dinh luat Raoult cho biet quan he dinh Wong Oita n6ng dO va d0 nhiet dong dac cila dung dich qua pinking trinh: Atd = Kd x m (8-24) O day, Atd = t(d) (dm) - td (dd) goi la dQ nhiet dQ &Ong dac cUa dung dich vdi t; (dm) la nhiet di) (tong dac cila dung moi nguyen chat to (dd) la nhiet &Ong dac cila dung dich m la n6ng dQ molan dm chat tan dung dich Kd la hang soy &Ong dac ciia dung moi, goi la hang s6 nhiet d413 dong dac molan, vi m = thi Atd = Kd Bang 8.12 cho biet nhiet dQ &Ong dac va Kd do'i vdi mot s6 dung moi Kd(H20) = 1,86 la mot gia tri nhQ, vi du: mol glucose hoac 0,5 mol NaC1 hoac 0,33 mol K2SO4 hoac tat ca cac dung dich co mol tieu phan chat tan kg nuoc deu dong dac d -1,86°C (n6u xem gin cluing he s6 hoat di) bang 1) (113) S6 mol C,H2O, = -= 16,1 mol C21-1602 62,07g C2 H 60, /lmol C2 H 0, 1kgC2 H 0, (10s g/lkg) 1000 X W2 M2 = Ks x = 0,51 x x At, 100 x (100,149 -100) 1000 x 10 Mot s6 van dung cila dinh luat Raoult ve cl8 tang nhiet d8 soi va nhiet cl8 &Ong dac cila dung dich + Bai tap van dung 1: Trong 4450 g nude có chlia kg chat ch6ng thing quen thu8‘c la glucol etylen (C2H602) Cho bievt nhiet sOi va nhiet d8 Bong dac ciia dung dich nay? Gid is mol chai tan 16,1mol C H 02 kg dung mOi 4450g H O x 1kg/103 g \= 3,62 mol C21-1602/1kg H2O = 3,62 m Ap dung phtiong trinh (8-23) vdi Ks(H20) = 0,512 (bang 8.12): At, = 0,512 (°C/m) x 3,62 m = 1,85°C (dd) = t s (dm) + At = 100°C + 1,85°C = 101,85°C Ap dung phuong trinh (8-24) vdi Kd(H20) = 1,86 (°C/m): Atd = 1,86 (Tim) x 3,62 m = 6,73°C ea) (dd) = td (d,„) - Atd = 0°C - 6,73°C = -6,73°C (Co nhiet dO d8ng dac thap nen_ dung dich duds sit dung de ch6ng dung nhi6u thiet bi) + Bai tap van dung 2: Dung dich chlia lOg sacarose 100g nude có nhi4 d8 soi la 100,149°C Tinh kh6i Wong phan tit sacarose? Gid is Pluiong trinh (8-23) có the vie't dttdi dang khac: W,/ M 2 1000 X W2 At, = Ks x m = Ks = K (8-25) W /1000 Ks M2 WI Trong do, M2 la phan tit Wong cila chat tan (g/mol) W2 la kh6i Wong (g) chat tan W1 la khoi Wong (g) dung moi Rut ra: N8ng d8 molan (114) + Bai tap van dung 3: D6 nhigt d6 dong dac ciia dung dich 2g 1,3- dinitrobenzen boa tan 100g benzen la 0,6095°C Tinh kh6i Wong phan tii cila 1,3-dinitrobenzen? Gicii: Phtiong trinh (8-24) c6 the vigt clang khac: 1000 x W Atd = Kd Kd x /M = K4 x (8-26) M2 X WI o day, W1, W2 va M2 coy nghia Wong ti.1 nlitt CI pinking trinh (8-25) cila vi du tren Vi dung moi cila dung dich la benzen nen Ka = 5,12 (xem bang 8.12) dtioc dita vao bieu thiic tinh: 1000 X W2 1000 X M2 = Kd x = 5,12 x = 168 g/mol W1 x At d 100 x 0,6095 - Trong ky- thuat va dai song, quy luat d6 nhigt d6 &rig dac cua dung dich c6 nhigu van dung hi u Ich + TtiOng of glycol etylen (xem bai tap van dung d tren), glycerol (C3H803) cang c6 dac tinh de tan nuoc va khong bay hoi nhO hinh nhigu lien kgt hydro nen cling la chat ch6ng dong tot Cac loci ca Bac c-kic tai san xugt cci th4 thong mot Wong lon glycerol de thap nhigt d6 dong dac cua mau, nha mau cua chung kh6ng bi dong dac a nhigt thap dudi 0°C + Cho mai an vao thimg ntidc der c6 the tao mot ngan sinh han thap nhigt xu6ng thap hon 0°C; hoac rai cac mu6i NaC1, CaC12 van nhfing ndi khong muo'n nit& (long bang (CaC12 c6 AHht < nen nhigt toa no hoer tan gop phan lam tan nu& der dong bang) 2.4 Ap su'dt therm thgu Dinh lulat Van't Hoff - Sti thdrn Theo quy luat tang Entropy, cac phan tii khong ngifng chuygn d6ng va c6 khuynh huong tai nhien chiem toan b6 khOng gian ch-Cia no Chuygn d6ng nay goi la su' khudch tan Hign tvdng cang toting tai hinh dung dich: chat tan khugch tan vao toan b6 dung moi de tao mot he d6ng nhat: Neu cho dung dich n6ng d6 khac tiep xtic NT& (vi du, mot cO'c Ong san mot dung dich &fang dam dac, to rot can than len no mot dung dich &thing loang hon) thi sau mot thai gian nao (do cac phan tit chat tan khugch tan tit dung dich dam dac sang dung dich loang, va ngtidc lai, cac phan ti.).1 dung moi khugch tan tit dung dich loang, giau no hon, vao dung dich (115) Dung dich Chu* dung moi qua many Phan tit chat tan Phan tit dung moi Mang ban tham dam dac), nang cua cac call tit' (chat tan va dung mai) dude san bang a moi phan cila he Khi Entropy cila he dat dude cue dai va ski khu6ch tan ngiing lai Ste khue'ch tan ceta chat tan va dung moi vdo c e'san bang ndng cho goi la su' khuech tan chieu Ski vi."c se khac, n6u giiia hai dung dich c6 n6ng khac duoc n.gan each bang mat mang ban therm - mang cho pile') chi cac phan tit dung mai qua lai chi6u, nhung cac tieu phan chat tan thi khang th6 di qua Su' khue'ch tan chi cita dung mai qua- mang ban therm goi la sti therm thdu [Mat binh hinh tru bang dat set c6 nhi6u l6 nhO dude tam dung dich Bong sulfat (CuSO4), sau nhiing vao dung dich kali hexacyanoferat (II) (K4[Fe(CN)6]) thi tai cac l6 cua binh c6 ket tua d6ng hexacyanoferat (II) (Cu2[Fe(CN)6]); mang cellophan; cac mang t6 bao, cac vach ngan gicia cac cd quan cd the clang vat, thuc vat d6u la nhung mang c6 tinh ban tharn] - Ap suet than) thau: Ap suet tham thau A Ap suet ch6ng Iai ski tang the tich C Hinh 8.10 Sti hinh ap suet them theu A Trong qua trinh them thou, mot dung dich va mot dung moi (hogc cg dung dich CO Wang d6 khac nhau) dude phan each bgng mot mang ban them Hinh a'nh pilaf) to (hinh dtkii) chi cac phan tit dung moi chuyen vac) dung dich nhieu hon B Ket qua 16 the tich dung dich tang, Wang d6 cc:1'a nO gi6m Su chenh loch d6 cao giCia hai chat long tticing Ong v6i ap suet them theu (7z) C Ap suet them thau dude dinh nghTa la ap suet can thiet tac dung len dung dich de no khOng tang the tich (116) hcin di qua Do c6 mat cdc ti6u phan chat tan, so phan tit nitric to tap a phia mang chita dung dich it hdn, nen s6 phan tit rut& a phia mang ben (phia nttOc tinh khiet) chuyen vao dung dich lon hdn cfing don vi th6i gian, lam tang the tich ciia dung dich va lam loang no Kgt qua la chigu cao cua cot dung dich tang len, dia cot nitric nguyen chat thap xu6ng Khi ap suet thug tinh ciia dung dich (Wong ling vdi Wong ciia dung dich cot mite cao hon) du luc day lin brit mot s6 phan tit nude chuygn vao dung dich thi mot trang thai can bang dtioc thigt lap, to-c d6 cila dung //led (so phan tit rut& ding thai gian) chuygn qua mang chigu bang Ap suet thug tinh hinh thknh digu kin vay dtioc goi la ap melt therm theiu (it) ciia dung dich, no Wang ling vOi mot ap suet ngoai can thigt dat len bg mat dung dich dg ngan than sit di chuyen cua rat& tit dung moi vao dung dich Can ch-6 Y rang, cap suet therm thdu chi phu thuOc veto so lu'dng, ma khong phu thuo2c vao bdn chat clia ccic tdu phan chat tan dung dich (vi vay, no la tinh chat Ong hop Wang ti nint cdc tinh chat cua dung dich tuan theo cdc dinh luat Raoult der lieu a phia tren) GiOng vdi cac phan tit ly Wang, cdc tigu phan chat tan dung dich rat loang d xa va khong tuang tac vdi Doi vdi nhiing dung dich rat loang - dung dich ly tuang, suet them thau (T) dttoc tinh theo phttong trinh cua dinh luat Van't Hoff: a day: mol." K Ap suet than' thau tang theo sit tang cila nhiet d6, vi T lam tang s6 va cham dung moi - mang mot don vi thai gian it cling tang theo sit tang n6ng M, vi M 16n clan dgn stt thilc day manh hdn qud trinh pha loang de tang entropy dung dich Stt giOng giita phttong trinh (8-27) vdi pinking trinh trang thdi ly Wang (PV = nRT, hoac P — nRT ) cung V khong ddng ngac nhien, 136i vi ca hai dgu the hien sit Wang quan Oita ap suet cue mot he vdi n6ng va nhiet ciia no Khdc la a ch6, ap suet gay bai sit va cham giiia cdc phan tit vdi va vOi binh, dp suet them than gay bai sit chenh lech n6ng d6 dung moi (tile la chenh Lech thg hod hoc t ciia dung moi tip xiic -qua mang ban them) Khi dung dich rat loang, n6ng d6 M m (vi khol Wong rieng dia dung dich nitric luc d6 d kg/L), nen: 7C = -nR T = MRT (8-27) V n la s6 mol chat tan the tich V (lit) ciia dung dich, vay n/V la n6ng d6 mol/L, n6ng dO M T la nhiet d6 tuyet dOi cita dung dich L.atm (117) it = mRT (8-28) GiOng nhU 1ST Wang d di6u kien tieu chuan, mol chat tan c3 0°C (273°K) mu6n c6 ap suat them than latm thi the tich dung dich phai la 22,4 L, mol x 0,082 L.atm x 273° K nRT mol." K V (L) = = 22,4 L 1 atm Ap suat them thau la bik hien cila nhieu loai hic quan Vi du, dung dich 1,0 M hoac 1,0 m cua cac chat khong din ly va khang bay hcii nueic a 0°C c6 it ,==, 22,4 atm + Trong Y-Dtioc ngtfai ta quen dung ddn vi khac cua it la Osmols (viet tat Osm) voi dinh nghia: Osmols la ap suat them thati cila dung dich chlia mol (gam) chat tan khang dien ly kg milk tinh khiet hoac kg dung moi tinh khiet (tile la dung dich m theo ang molan) 116c thap phan cua Osmols thuOng duoc std dung la milliOsmols (viet tat mOsm) voi quy dai: 1 Osm = 1000 mOsm - Vai tr6 cua alp suat them thau: Bao quanh moi t6 bao song la nhfing mang ban them quan nhat Vi very, vai tro cua ap suat them thau duoc tim they moi ndi thien nhien va cac gi6i sinh vat + Su them thau la mat nhung &tang co ban de cac phan tit nu& (dung mai) vao - cac t6 bao qua mang ban them Co nhfing mang cling cho phep mat s6 ion va tieu phan chat tan n116 di qua mat each chon loc Trong cac, t6 bao song la nhfing dung dich - bad Wong Ngtfai ta goi mat dung dich la dang tru'dng neu dung dich c6 cling tieing cac tieu phan chat tan nhtt dich to bac) Vi ap suat tham thau ngoai va t6 bao bang nhau, s6 phan tit node vao - t6 bac) v6i cling t6c do, nen dung dich clang tracing cac t6 bao gilt nguyen hinh clang binh thuong„ Mat dung dich goi la nhu'o'c tru'o'ng nting cac tieu phan chat tan cila no thap hdn dich t6 bao Do ap suat them than not bac) 16n, nude bi keo vao t6 bao VI the, cac t6 bao dat dung dich nhttoc trtiOng bi tnidng phang va va Nguoc lai, dung dich u'u truVng la dung dich c6 nting cac tieu phan chat tan 16n hdn dich t6 bao Neu dat cac to bao vao mat dung dich nlru the, node bi ht t cac to bao va lam cho thong teo lei Nguyen nhan la ap suat therm than ngoai ban lon hon ap suet them thau not bac) + Ap suet them than binh thuang cua mau va cua hau het cac dich (118) Trong chuyen nganh Y-Dtioc, nguoi ta goi cac dung dich clang trilcing, -au tracing hoac nhuOc tnidng la so v6i ap suet therm thau cua mau nguai gioi han neu tren Neu sai khac atm hoac 50 mOsm so yen gia tri trung binh (7,3 atm hoac 286 mOsm) IA bleu hien cila nhfing benh 1ST nang (nhu benh gan, suy than, shock tan mau, ure huyet, nhiem dOc ) B6n ion sinh hoc thigt 34u: Na+, Ic+, Mg' va Ca' - c6 vai trO digu tiet the tich dich cd the a ngu6i va moi &Ong vat Ion Na+ chiem hon 90 mol% dm tat ca cac cation ngoai bao N6ng cao se keo nuoc kh6i to bao b6i ap suet therm thau ngoai bao Ion NOng clO thap, nu& bi but vao to bao b6i ap suet nOi bao cao Very, vai tr.() co ban cita M.+ la digu chinh the tich nLtdc co the, mot nhfing vai tro cci ban dia than la digu chinh n6ng dO Na+ thong qua co chg digu tigt huygt ap - than kinh - hormon Dung dich truygn tinh mach voi the tich lon de nuoi duong (vi du, dung dich glucose), de tri the tich mau va can bang dien giai (vi du, dung dich NaCl), hoac de digu tri benh (cac dung dich thu6c) luOn can phai clang truong v6i mau ngu6i, nghia la c6 ap suet therm thau gioi han 7,0 - 7,5 atm de cac to bao hang cdu khong bi truong vd hoac teo lai (vi du, dung dich glucose 5%; NaC1 0,9% la nhfing dung dich Bang trttong) ThuOc nh6 mat, the mat phai clang truong voi dich mat de khong lam bign dOi the tich cac to bao giac mac (vi du, rnt6c mu6i sinh ly la dung dich NaC1 0,15M - Wong &tong 0,9%, dung de rita mat) Nguoc lai, nguai ta tao m8i truang c6 ap suet therm thau rat lon de bao quern cac &toe chat cluoc lau dai, vi mOi trUong ay cac t6 bao vi khuan, bao tit nem bi but kiet nude va chgt (vi du, sire) thu6c la dung dich dam clac - hon 60% &tang trang co chiia cac duoc chat, dich chigt duoc lieu va chat thorn) ThuOc ldi tieu therm than co co the lam tang ap suet them thau 6ng than de thu but nhigu nu& ve than r6i bai xuat qua nu6c tieu Vi du, cac dung dich tiem tinh mach cila ure, manitol, sucrose; cac thu6c furosemid, chlothiazid gay ldi tieu digu tri phn lido, tang huygt ap, tang nhan ap (glocom cap), phu phOi va de deo thai cac chat , clot qua than Benh nhan suy than nang can dtioc them tech mai loai b6 cac san pham chuyen hod (nhu creatinin, ure, acid uric), nhung gift lai cac chat can thigt cho co the (nlau glucose, chat dien giai, acid amin) May chay than nhan tao la mot he thong mang ban therm clac biet thiic hien qua trinh therm tech matt (119) TC khong the sang nttdc ngot có Ai) su'at thanithau.nhO (chi khoang atm) va Ngam mat ong cac:dUcic lieu quy; hoac'itdp mot lop mu6i len' thuc phOrn de bao quan 1a.0 dai la chfa tren co the diet khuan nhti vi du v6 siro not tren Neu gay met ap lac tren dung dich 16n hon ap 'sua.'t therm thau- Cila no thi dung rnoi bi day ngttoc khOi dung dich qua:mai-1g ban therm Qua trinh goi la sit thOrn than nguoc, Hien nay, phtiong phap them that' ngtioc qua mang ban therm (lam bang seri cellulose acetat hoac polyamit) dude van dung n037 cang ph6 hien d nhieu qu6c gia de bier] nude bien nuOc ngot vi quy trinh san xuat don gian, khong ban nhiet chttng cat, 'chi phi thap [theo plitiOng phap nay, cac nha may ph6 Sarasota, Florida (my), hoc cite mace yang Vinh nhu CO:oet, A-rap Xe-Ut clang san xuat nhieu trieu gallon nuOc m6i (1 gallon lit)] - Bai tap van dung 1: Vi dung dich glucose Ccfl,206 (M = 180) dUng tiern truy6n lung ldn vao tinh mach ngoai vi cho benh'nhan de bit mat nu& hoac de nuoi,duang, phai co n6ng d6 5% intdc? Gidi: Xem gen thing dung dich glucose %o, co d = 1,0 g/mL Ira sit dung phticing trinh (8-27): zc = —RT de tinh toan Luu y rang, day T phai lay phis hop V vOi than•nhiet tiguoi binh thtiong la 37°C Dua cite s6 lieu vao phutong trinh, thu duoc: \= bira 7,06 atm rs Vay, dung dich glucose' dung tiem truy6n hicing lon phai c6 n6n:g la 5% vi dp suet therm thau cilano,dang trtiong veil man ngttoi - Bai tap van dung 2:'Pepsin la rn'et enzym phan giai protein c6 rnaftrong 6ng tieu hoer: Met q-n'au 0,500 g pepsin da'tinh the 30,0 mL thing dich nitoc 'có apsuat thOrn than la 8,92 nimHg'a 27;0°C:Tinh phan-ttit luring cua pepsin 3.1; , ;':)1 1.13 fdhlti - 8"Ap dung pliang trinh (8-27).: 'gill; 1311°11 fintkl 611.1 :a Di'-:!f.) fn ri'Ab !limb El 01.0 ,iflo IA) ftlf, TC = MRT = RT hoac n = OE:,) f!;“ V rif)tb finfirwri Am vii rio11-1 pita cite da heti vao plaucing t ' h h rm , c uyc yen Q1 'd- 02)"(15 g ti.anh atm de co aing danvf ;VoiTR,'thu &roc: IIJB cS ficoilA) cr.61d Sg C61-112 06 1000mL f12 0/1 180g C61-112 067m01 100mL H x 0,082 L.atm (120) 47 -T;,,oartripmeir porippipirrre_ atrii Iilinflb I / 8,92unHgx 3,03oo fir: I 760mmfg 1,43 x .atm 0,082 300c) K b ) rift) 0, ,, (;)Yrrg o9dt dub " .f`H '1! dii mol.`) K), 10-5 mol pepsin f It Ion trung binh cna cac protein.: n 1611 Chu Y rang, nhiet Bong dac cna dung dich pepsin no'ng loang nhu vay chi vao khoang 0;0009°C - met gia tri rat kho Wang chinh xac, dp swat therm than 8,92 mmHg duoc' xac'dinh Met each de clang va kha don gian Di6u giai thich vi nguoi to thuong xac dinh phan tip luring cac chat nho dinh luat Van't Hoff v6 dp seat thanith.au., 3 TINH CHAT CUA DUNG DICH CAC CHAT DIE' N LY :Cac: tinh chat cna dung didh tuan theo dinh lua.t Raoultva.Van't: Hoff, chi phn thuec vao :s6.hat (s6 ti6u phan), chat tan :mot kholluong xac, cna dung mei w, Nhu vay,.chnng.ta di kie'n rang de tang nhiet soi (A.t.$);cna dung dich NaC1 0,050 m mioc se la 04) hailan dung dich glucose 0,050, a vi m6i don vi cong thfic NaC1 dien ly:tach hai ;phan (hai ian:Na'i va the met he so gia tang can duck dtta: vao cac phtiongtrinh cna.Raoult varVan't Hoff d6i vdi dung dich cac chat dien ly Do he so Van't Hoff, (i).; met: q7 gifia gia tai cac tinh chat dude tren thug n.ghiem dol vdi, dung dich., chat dien ly va gia tri ay dude tinh theo cac pfiti6ng trinhd6i*i.eil dung dich chat khong dien ly li 9nothil Gia tri duos cho dung dich chat dien ly •1 , : " i (lob i Sri Vi EL 601 11.1;011 Gia,,tri tinh duccc cho dung dioli:04t,khOng dien ly, 61,j grin nth' Nliff vay, de tinh cac dai luring '&4 trUng 'cho dung dieh chat diefi'ly, s0' it can n dude nhaii van' 'cac rihtfong trinh:.'" "9V- Lj g fi ,N"-(-" "1E-) 991i -60.14- fhl± c_.{.Lui 1ft oh D G1/1 grimb gnoll irud guii;r0 p.ao ha-ap sprat hc4: „ L.-3 ucI ,E- 4:k27} iiNacgt-pmdrudril ot.;J Ern 13 sb ii; id` Doi d6 tang nhiet soi: Ats: — iff -1 in6J-.4)bdan kifiri nod 116irla fro= r,1114 .1'1101 rnith" oo "rum risvllp POi vOi nhiet cm) dong ! „ , - I ) grfu.on 11.1i0f1 had DoIvOi a.p suat tham Llii) r{oIi nib tied cfsgoiib 41-1 NhU'vay, 0,500 g pepsin la 1,43 x 10-5 mol Tin kh6i luOng mol cna no: 0,500 g ifb ? g/mol .3,5- g/rnol lig is, 1,4.3 . 10-5 mol rfl 01 16.A doll) (121) Ngu dung dich dien ly la ty Wang, nghia la moi thin vi ding thitc cua chat tan dien ly hoan toan cac ion, thi i = cho NaCl; i = cho Mg(NO3)2; i = cho FeC13 Thiic to cho bigt hau hgt cac dung dich dien ly la khong 15T Wang nen i nhO hdn cac s6 du doan tren Vi du, tren thtic nghiem thi dung dich NaC1 0,050 m da neu o tren cho Ats = 0,049°C, dung dich glucose 0,050 m khong dien ly (i = 1) tinh theo phiicing trInh (8-23) cho 0,026°C, ta tinh ditOc: At cua dung dich NaC10,050 m 0,049° C 1 = Ats cua dung dich glucose 0,050 m 0,026° C = 1,9 Nhit vAy, i = 1,9 chit khong phai bang nhu du doan Thong tit, dung dich KBr 0,10 m va KBr 1,0 m nude cho Atd duoc tren thitc nghiem lan liidt la 0,349°C va 3,29°C, tinh theo pinking trinh (8-24) cho cac chit khong dien ly cling a hai n6ng Ay (0,1 m va 1,0 m) tuong ling la 0,186°C va 1,86°C, \ay: 0,349° C poi voi dung dich KBr 0,10 in: = 1,88 0,186° C 329°C lJoi voi dung dich KBr 1,0 m: i = — 1,77 1,86°C O day, ta có nhAn xet: ding met chAt dien ly, ang (16 thAp i lon hon Thiic t6 la, a n6ng to tang loang cac dung dich dien ly tang gdn toi ly titang, nghia la i tang gdn toi nhung s6 nguyen dung bang s6 ion tach to met don vi tong thitc cua chat dien ly da cho Bang 8.14 cho bigt cac gia tri i dia dung dich ly Wang va i cac dung dich có n6ng de khac doi vdi cac chAt dien ly manh hoa tan nuoc Chu Y la, cac ch'At dien ly ygu nu& có i > chi t it; cac chAt kh6ng dien ly hoa tan nu& hoac cac chat tan hoa tan cac dung moi khong phai nit& có he s6 i = (122) de hinh nen tang sai lech voi he so i 1ST tu6ng N6ng d6 hoat Ong thuc, goi la hoat d6 hay n6ng d6 hieu dung cila chat tan luon nh6 hdn n6ng tinh theo cong thiic, nen i thuc nghiem luon nh6 hdn i 1ST tuang Bing 8.13 HO s6 Van't Hoff i thu'c to Ira ly twang cua cac chat kheing dien ly va dian ly manh dung rneji nu'dc Hop chgt i cho dung dich 1,0 m cho dung dich 0,10 m i cho dung dich 0,050 m • Kh6ng die'n ly Glucose, C6H1206 Sucrose, C12H22011 1,00 (19 twang) 1,00 1,00 1,00 (19 tu'ang) 1,00 1,00 1,00 (19 Wang) 1,00 1,00 • ion/don vi cong thac KBr NaC1 2,00 (19 Wang) 1,77 1,83 2,00 (19 Wang) 1,88 1,87 2,00 (19 tireing) 1,90 • ion/don vi cong thCrc K2CO3 K2CrO4 MgCl2 3,00 (19 twang) 2,39 1,95 3,00 (19 tu'ong) 2,45 2,39 3,00 (19 Wong) 2,70 • ion/don vi cong thCrc K3[Fe(CN)6] FeCl3 4,00 (19 twang) 4,00 (l tilling) 2,85 4,00 (19 hieing) 3,40 Bai tap van dung: Acid lactic, C2H4(OH)COOH, dtioc tan siia chua N6 cang duoc hinh cd van Ong g'Ang sfic va gay cam gide dau D6 mot acid yeu don chile, vi vay clang la chat dien ly yeu Nhiet d6 &mg dac cUa dung dich acid lactic 0,0100 m nu& la -0,0206°C Hay: a Tinh he so i cila dung dich acid n6ng c16 da cho b Tinh % s6 phan di acid da ion hoa dung dich Gicii: a Trude het tinh m(hieu dung) tiic n6ng c16 hoat d6ng thiic Atd (thue I:6' do) = Kd (H20) X m(hieu dung) (hien dung) At d (auk L6 do) 0°C - (-0,0206°C) - 0,0111M (123) ,■-affij (job L;;}Li ,1 6=D &ill oh T4 {16“ ,Q,0100 m 'Urlt cho KST hieu acid lactic = HA Goi xJa nong riiolaq cia aeid 1actic da'dien ly cac ion (cta- ion hod) Theo dO, co the lap cac quan h sau: r , , HA A 00:r Ban du: 0,0100 m 0 00 r Bien doi -x m +x m +x m Cuoi ciing: (0,100 - x) m 'X m x m Mai(eu dung) = MHA m m A r."31:30 \= (0,0100 - M + xm xm 0,0111 M - - , sob\1101E (prrco : Rut ra, x = 0,0011 m = M(ion hoa) 0, m Vb % dien ly = 0011 x 100 % 11 % A 0,0100 m Vay, chi có 11% s6 phantif acid lactic hob tan dienly cac ion H+ vb ef2814(OH)C00- Con 89% khong dien ly nhm dang phan tit riguYen yen dung dich "g11011 ` )Y.ij HOCYJ 171 0/ 11 J ) BV otra ifi)v ifi 1iOti d11ii :-0 TOil) gilfp) if loril - fi )tiJfl f1Ofl m 0010,0 flob 1/61, : fl) (tb ±.db JO 311 di-in ii yfift 15;2 ,:r!:` 261 (-)b %nor' f.)bi f oh „i rri f5r1 )6`.1"sir.r 1 1111110,0 kT ) 000,0-) - D 0 M D °081 0;30, o111 (124) Mc:1C TIEU 1 Gidi thich cac khcii niem a, i, A, K, hoat (a) vet he so'hoat d(f) Lap du'cjc ccic phu'o'ng trinh quan he va tinh ctu'o'c gici tri ceict cdc ctai lu'o'ng 2 Trinh bay cdc diem giong vet khdc cact ly thuYet ye acid - base 3 Vdn dung thuyet Bronsted - Lowry, tinh du'vc pH cua mot so dung dich cac chat trong dung mai nu'oec 4 Trinh bay khcii niem vj dem,, chi thi mew vet tich ,so" tan Chi n,hieng van dung thu'c te"ceta cdc khdi niem áy r4ib (ILI) CC th (nor qiyi) Ito! i0s1 -(4114.111 61-II 14111A ILI feiriA IIIIII DE/1 &Laub ifyi c1.yI 1.01 1'AP:111 ';e1.3 11 Chung ;1-1 Dbun:t.A.acrlf -gram ic171 d'Ab p,1111b -gnord noi giuy; DUNG DICH CHAT DIEN LY 1A ci"i"/ "11 td nYfd1i ■;e:1.17 1; 1lor 171 'Orb i;od Ib yMb (2-() gnOinig- not Id 1:.ffi ,D6'1.111 -gra's 90:0' rHJ (JAI )/7.4") (16cf>1 'Ff rm! ,•2ri- i-s".-;t 71.sTft (xl) ,r1 nib M{ t Nguyen nhan chinh ca sli din ly phan ti cac ion ttiOng tac giüa phan t chat dien ly va cac 14-,40,ta chmg moi, dgAqt0 than-1110.0, i0.7v,s010Atc hoci (trong dung mei noi chung) hodc cac ion hydrat hod (trong dung mei nit6c) — Khi cac chat dien ly tan nvoc, chting ton tai dad clang ion (1,A)dung dich bi"eu thi theo nhiing phdong trinh: ,mb'r NaC1 + aq Na (aq) + Cl (,„i) (9-1) HC1 + H20 -> + jj'.1•""LIfl 1i finib (9-2) no! 141I.A0 H.3cr.,,Lp, )61,c,00_ - A9_3) d-r"31-0 iii& khong xac 'clinIM) tigted'nediVd b© qua de laM" cax t.)n 'g1(011 .1101 ',9,n0.) 1dy guk.;.b fino 1111 u6i(-1 (1.11fij rbifign: 10 no') Ov od 11k/ 1)1:)1; '.)11") B re(J iV LimODi.v) iL lib) 'Oa &V 1.611111 11 k: ;( 11/0 t:i21 ,)td iv T-11.41, 1 TRANG THAI CUA CHAT DIE N L Y TR, ONG DUNG DI C [,( I/fp ),A 1:1 Dinh nghia - Phan loai chdt dien ISI31) 3;" Lid) 161" ot" — Nhiing chat hod tan dung m6i ma cac phan ti1 cia chting phan ly ion goi la chat dien ly (125) NaC1 tinh khigt la tinh the c6 mang Midi ion (hop chat ion) nen (fan dien nong chay /Woe, nuoc se boa tan tinh thg NaC1 va tach rai cac ion dung dich HC1 tinh khigt ton tai chu ygu a dang phan -at trung hoa (hop chat ceng hod tri) chit khong phai g6m s'an cac ion, nen khOng dan dien Tuy nhien, phan itng vdi nu6c, HC1 bi ion hoa (dien ly) theo pinking trinh (9-2) O day chu rang, ion H+ khong ton tai d6c lap dung dich nti6c N6 phan ling hoan toan vdi met phan tit H2O (qua met cap electron ti do) tao ion H30+ goi let ion hydroni hoac ion oxoni Ion H30+ c6 cau true hinh thap gigng nhu NH3 Ngoai H30÷, dung dich ton tai cac dang hydrat hod khac cua proton (IV) NaC1 va HC1 la nhung chat dien ly manh vi chung gan nhu ton tai hoar' toan &Lich dang ion dung dich nil& d nOng trung binh Cac acid vo cO: HC1, HBr, HI, HNO3, H2SO4, HC1O4, HC1O3; cac base vo cd nhom kim loci kigm, kim th6: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)9; hau hgt cac mu6i vo cci va hiiu cci dgu thuec nhom chat dien ly manh Tra lai phan ling (9-3), acid acetic la met chat dien ly ygu, mai ten thuan nghich pinking trinh bigu thi can bang giiia clang phan tit va dang ion Hau hgt cac acid va base hilu co; tat ca cac acid va base vo cci lai (trif nhang acid va base da kg d trgn); mot s6 it mugi ye cci (chi acetat, Hg(CN)2, HgC12, Hg2I2, Hg2Br2) va cac ion phlic bgn (nhu [Hg(NH3)2]+, [Cu(NH3)4]2+, [Fe(CN)6]3+, [HgI,]2+, ) dgu nhiing chat dien ly ye-u Sit phan chia cac chat then ly manh va ygu chi la Wong dal, vi de dien ly phu thuec vao n6ng de chat tan, tinh chat cila dung mei va nhigu ygu to khac 1.2 DO dien ly (a) 1.2.1 Dinh nghia - Cac ye-u to tinh hming Bo dien ly a la tS'T so ciia so phan tit dien ly va tong so phan tit hoa tan: S6 phan tix dien ly (9-4) Tong s6 phan tir hoa tan dinh nghia tren, suy a (126) Nguai ta cling bidu thi a bang % va qui uoc, ngu dung dich chat c6 ang d8 0,10N d 25°C ma: 30% la chat dien ly manh 3% < a < 30% la chat dien ly trung binh a < 3% la chat dien ly ydu - D6 dien ly phu thutic vac) cac ygu + Bcin chat dui chdt tan Theo chigu sap xdp tii phan to ion, phan tii phan clic nhigu hay it, phan tis khong phan cuc, not chung su dien ly bat 10i dan dgn khong thd dien ly Sts then ly cua chat tan phu thu6c cu the vao ban chat cua moi chat dien ly, nhii ban kinh va dien tich cila ion, d6 phan chic cua ion va phan tip, nang Wong mang Midi, ski hinh cac lien kgt phu chat tan -• dung moi NhUng ban chat ay lam cho moi chgt diOn ly c6 mot gia tri a rieng ding mot dung moi va d cungnhiet + Bdn chat cua dung moi Dung moi phan chic tang lon (phan tii c6 momen cult ion) gay ski dien ly tang manh; dung moi khong phan cuc (liphan = 0) thi khong gay rasu phan ly chat tan Dd so sanh kha nang ion hod khac cua cac dung moi, nguOi ta dung dai hiOng goi la hang so diOn mai e, d6 la mot so (khong this nguyen) chi cho bigt list tac dung gitta hai dien tich cua phan to dat dung moi nhO hdn bao n.hieu Lan so voi laic tac dung than khong E phu thu6c vao d6 phan cue pt, cUa nhUng phan tit dung moi c tang lon dung moi tang phan cuc va gay su ion hod tang manh, a tang lon Bang 9.1 ghi hang so (hen moi cua mot so- dung moi thong dung 25°C Bang 9.1 Hang s6 cliOn moi e cua mot s6 dung moi 25°C Dung moi E Dung moi E Hydro cyanid 110,0 Ethyl acetat 6,0 N tiac 78,5 Chloroform 4,8 Glycerol 42,5 Diethyl ether 4,34 Methanol 32,6 Carbon disulfid 2,64 Ethanol 24,3 Toluen 2,38 Aceton 20,7 Benzen 2,27 Isopentanol 15,0 Carbon tetraclorid 2,23 1-Pentanol 14,0 Pentan 1,84 (127) Milk o dieu kien thtiong c6 E = 78,5 nen dung dich ntiOc, 14c but gifia cac ion se —79 ldn be lion so voi tinh the Ntioc c6 hang s6 dien moi lon nhat s6 cac dung moi thong dung, nen int& la dung moi rat tot hod tan rat nhieu chat khdc [mat khac can chu Y, n6u co su hinh hen ket phu, dac biet la hen ket hydro, gilia chat tan - dung moi thi hang so Bien moi E co khong gilt vai trO guy& dinh Vi du, HC1 ion hod rat manh trong ethanol (6 = 24,3) hon la hydro cyanid (E = 110,0) vi gifia HC1 -ethanol c6 hinh lien ket hydro, giiia,HC1 - HCN thi killing Theo to thdy, dac tinh rieng cad cau tit chat tan va dung moi c6 mot y nghia lon doi voi sit dien ly nini the nao] + Gici tri cUct a phu thudc ndng d6 Khi nemg dO cac ion dung dich tang, cluing de" va cham tai tao lai phan tit ban ddu, a giam Ng-0c lai, dung dich cang loang, a cang lOn Quan he gnia n6ng C va a duct thay lai dinh luat pha loang cita Ostwald + Gia tri caa a phu thu'Oc nhiet di) T Neu qua trinh dien ly thu nhiet (OH > 0) thi T T, a T va ngtioc lai Neu qua trinh dien ly phat nhiet (AH < 0) thi T C, a 4, va nglioc lai Nhv da biet, qua trinh hydrat hod la phat nhiet, nen nhin chung T T lam can tra qua trinh do, a Tuy nhien, nhiet hydrat hod ion khong cung cap du cho qud trinh dien ly thi viec be.; sung them nang lacing tit ben ngoai la can thigt, hic T T, cc T — Vi du 9.1: Nu& phan ly hap thu nhiet dang ke: H2O + H2O H30+ + OH- Ott = 55,9 kJ Vi vdy, dun ming, dO dien ly cua nude tang len manh Dieu c6 nghia lOn doi v6i nhieu phan itng dung dich mtoc + Su' có mat mot nhiing ion cang ten voi chat dien ly dung dich se lam giam di) dien ly a Bai vi, qud trinh dien ly cling thie't lap can bang gifia cac phan tit khong dien ly va cac ion dm no dung dich Khi co mat ion cang ten, can bang dien ly bi day lin lam a giam Vi du 9.2: CoC12 khan ritioc có mau xanh, la chat dien manh Khi dien ly mfoc, ion hydrat dia Co' có mau hang va dung dich thiet lap can bang: CoCl2 + aq CoNaq) + 2c1- (aq) (128) ,Khi them HC1 dac vao dung dich, tfic IA them rat nhigu ion cr, can bang bi day lui rat manh sang trai, Tan mitt dung dich ton tai chu you cac phan tip CoC12 khong dien ly, mau ciia dung dich chuy'en -al hang sang xanh Sit chuyan dich can bang dien ly rat thuang gap nghien cuu cac tinh chat cila dung dich Vi gia tri cila a phu thuac nhigu yau to nhu da ke tren, nen muan so sanh dien ly gifia cac chat can phai tign hanh ciing digu kien Bang 9.2 ghi tri s6 a cila mot s6 chat Bing 9.2 Gia tri de) dien ly a coa 1744 s6 chat a neing 0,10N dung dich nu'Uc va a 25°C Chgt dien ly a Tinh theo % Chat dien ly a Tinh theo % Acid Base HCI, HNO3 0,90 90 KOH, NaOH 0,90-0,95 90-95 H2SO4 0,60 60 Ba(OH)2 0,77 77 HF 0,08 NH4OH 0,014 1,4 CH3COOH 0,014 1,4 H2003 0,0017 0,17 Mu6i HCN 0,0001 0,01 KCI 0,86 86 H2O 1,8.10-9 1,8.10-7 MgSO4 0,45 45 1.2.2 Quan he giiia a va i • Neu cho m phan tit vao mat the tich nvoc, gia thiat masi phan tit phan ly y ion, va a IA dien ly, thi: ma IA s6 phan tit phan ly, se tao may ion m(1-a) IA s6 phan tit khong phan ly Tang sa tiau phan dung dich = may + m(1-a) = m(1-a+ay) He s6 Van't Hoft: S6 tidu phan thuc có dung dich m (1 - a + ay) i = S6 phan tit hoa tan - rut ra: a = 1 (9-5) (129) y cila m6i chat da bigt (vi du, NaC1 c6 y =2; Na2SO4 coy = 3; Na3PO4 c6 y = 4; ), i c6 the xac dinh dUoc bang each AP, Atd, Ats, it Vay c6 the tinh &roc dO dien ly a (xem vi du a muc 3, chuong 8) 1.2.3 Quan he giita a va dan diet' (lacing luo'ng - Sti dan dien kim loai la electron, su clan dien dung dich la cac ion DO dan dien cua mot dung dich la nghich ciao cua dien tra cila dung dich d6 va &roc tinh bang don vi Q-1 (ohm-1) DO dan dien cUa dung dich dien ly tang lon dung dich tang nhigu ion va cac ion c6 tic chuyen dich lon Ngtrai ta dua mot dai Wong goi la dan dien du'ang lu'o'ng va duoc dinh nghia la dO dein dien cita mot dung dich CO the' tich vita del cha'a dumg lacing gam chdt tan bang binh dien phem co dien cute song song each 1cm x &roc tinh theo ding thfic: 1000 x C day, X (khi, chic cai Hy Lap) la dO d ran dien rieng - dO dan dien cila cm' dung dich va mang don vi Q-1.cm-1 Con V (cm3) la the tich dung dich chlia diking lacing gam (E) chat tan, goi la pha loang: 1000 cm3 /lit C Eilit v6i C la n6ng d6 &tong Wong Ngitai ta dien trei dia dung dien di qua dung dich nhiing digu kien nhat dinh va tinh dttoc dO clan dien rieng x Bigt dO,pha loang V, ta tinh ditoc x + Vi du 9.3: DO dan dien rieng x cua mot dung dich thutic n6ng dO 0,1N 25°C &roc la 0,0293 5I-1.cm-1 Tirrh dO dan dien throng liking x cira dung dich n6ng do Gicii Ap dung phuong trinh (9-6): 1000 x 0,0293 = 293 cm2.S2-1/E 0,1 Vay, dO dan dien &tong luong gap 10.000 lam dO &an dien rieng [nii6c tang tinh khigt, dan dien rieng tang nhO Nude tinh khigt chfia CO2 can bang vii Mai quygn c6 x = 0,8.10-6 52-1.cm-1 Nu6c tinh khigt thong thiiang x = 1.10-6 S2-'.cm-1 Con nil& rat tinh khigt x = 0,05.10-6 Q-1.cm-1] - Theo dinh nghia vg X., Wong chat dien ly la hang dinh va bang diking Wong gam Tuy vay, dung dich tang loang, nghia la V tang lon thi dO x = x.V cm2.Q-1/E (9-6) (130) dien ly a tang lon, so- ion the tich V tang len, do d'an dien doing luong X cling tang Nhung X khong tang mai theo pha loang V cila dung dich, ma clan tdi met gia tri xac dinh r6i khong thay cl6i nfia goi la chi clan dien clito'ng lu'o'ng a' ctc3 pha bating vo cling Theo thuyet dien ly ciia Arrhenius thi d'an dien duong Wong ty le thuan \Tad dien ly a cila chat tan: X = k.a, vOi k la he s6 ty le O loang ye ding, tat ca cac phan Cif phan ly ion (a = 1) va dan dien dat tdi tri s6 gioi han ale dai la X = k, do X = rut ra: x (9-7) - Nha dinh luat cua Kohlrausch v6 sit chuyen deng dec lap cila cac ion cJ de loang ye ding, ta tinh ctlfoc: \= + 1:: (9-8) 1:: la din dien cluong Wong cita cation va 1:: la clan dien dudng luong cila anion d loang vo ding 1° cila cac ion phu thuec vao kith thu8c, hydrat ciia ion, cling phu thuec vao nhiet va ban chat cila dung mei Dia vac) dinh luat cua Kohlrausch, ngtfai ta có phuong phap rieng de xac dinh tri s6 1° cho tong ion va lap bang Theo do, X cua m6i chat có met gia tri xac dinh Co the tim chua biet dm met chat bang cach tong hoac trii da biet cua nhfing chat then ly khac, nhu vi du sau + Vi du 9.4: De dan dien diking Wong cila acid phenolbarbituric (HP = C12H12N203, met thu6c an than, gay ngil va gian co van) ci dung dich loang ye tan la bao nhieu? Biet rang X (HC1) = 426,2; (NaP - mu6i dm HP) = 73,5 va (NaCl) = 126,5 cm2.0-1/E Gicii Theo dinh luat cua Kohlrausch [phuong trinh (9-8)], ta có: ko, (HP) = 1;- (a) va X„„ (HC1) + X (NaP) - Xn (NaC1) = \= H + 1"+ 1" + Cl - Na+ P- - 10 - 10 Cl - \= + 1;_ = (HP) (b) Vay (a) = (b), thay cac tri s6 vao thu ctuoc: X., (HP) = X (HC1) + (NaP) - X., (NaC1) (131) Nhti vay, di the xac dinh &toe (xem vi du 9.3) va X.co (xem vi du 9.4) nen to co the xac dinh difOc cc bat ky n6ng nao theo phliong trinh (9-7) va nha ding tinh &toe hang s6 dien ly K cua chat dien ly 34u + Vi du 9.5: Do d'an dien cila dung dich acid acetic loang vo ming 25°C la = 390,2 cm2.Q-1/E; &an dien cila dung dich acid acetic 6,0.10-3M la = 21,1 cm2.Q-1/E Tinh dien ly a ciia acid acetic n6ng do Gidi Thay cac dit lieu vao phtiong trinh (9-7), tim dtioc: 21,1 \= 0,054 hoac 5,4% 390,2 1.3 Hang so dien ly (K) cua chat dien ly ye-u Dinh luat pha loang cua Ostwald - Qua trinh dien ly nhung chat dien ly yeu la met qua trinh thuan nghich va thie't lap met can bang deng dung dich Sit dien ly hop chat MxAy có the bieudien bang phtiong trinh: MxAy x MY+ + y Ax- (9-9) Theo dinh luat tac dung khOi Wong cua Guldberg - Waage dp dung cho he can bang thi: K [MY-1- ]X [AX-]Y (9-10) [M X A Y ] Hang s6 can bang K goi la hang so dien ly KS7 hieu dau moc [ ] de chi n6ng de C (mol/L) cua cac cau tit d trang thai can bang Trvang hop x = y = 1, chat dien ly MxAy phan tit don gian MA va dien ly theo pinking trinh: MA + A- Goi C la n6ng mol/L lac ban dau, thi ltic can bang: [Mt] = = a C [MA] = (1 - a) C Vay, [M + ][A] ccC.aC [MA] (1- cc)C (9-11) (132) RUt ra: a 2 .0 1 - a (9-13) Vi K = const, nen pha loang lam giam n6ng C thi a tang va ti6n clan d6n Bieu thi (9-13) goi la dinh luett pha loang ceta Ostwald Cac chat dien ly y6u c6 a nhO thi c6 the xem - a a, hie do: K = a2C va a = (9-14) Biel a va C ta c6 the tinh gAn dUng hang s6 diOn ly K cua chgt diOn ly ye-u theo bi6u thfic (9-13) hoa.'c (9-14), va ngtroc lai c6 the tinh throe a biet K + Vi du 9.6: vi du 9.5 da tim throe a = 0,054 dm acid acetic n6ng d6 6,0.10-3 M Dila cac tri s6 vao bieu thirc (9-13) de tinh gdn dung hang s6 di6n ly K cho acid acetic 25°C: 0,0542 x 6.10-3 = 1,85.10-5 - 0,054 - Hang so di'On ly K let mot dai luvng rieng cho moi chat dien ly CS nhiet khong doi, mot dung riled nhat dinh, K la dai ltiong khong doi K lon chat dien ly phan ly nhieu, K be chat dien ly phan ly kern Vi K chi phu thu6c van nhiet d6, khong phu thu6c vao n6ng d6 nen no dac trung cho mot chat dien ly ktiach quan hon la dien ly a Chang han, 25°C nguoi ta tim thgy cac gia tri a va K cUa CH3COOH nhu sau: C (mol/L) 0,001 0,005 0,01 0,05 0,10 0,20 a 0,124 0,060 0,042 0,019 0,014 0,0095 K.10-5 1,80 1,82 • 1,83 1,85 1,86 • 1,81 Ta thay, n6ng C thay d6i, a bie'n d6i rat 16n, K c6 th6 xem la hang dinh Vi tri s6 cua K the hien y6u - manh dia chat dien ly nen no cling ducic dung de phan loci cac chat: + Chat dien ly rat y6u: K 104° (vi du, H20, HCN, phenol, anilin ) + Chat dien ly y6u: K 10-5 + 10-9 (vi du, CH3COOH, NH4OH) + Chat dien ly trung binh: K 10-2 -:- 10' (vi du, H3PO4, CHC12COOH, Ca(OH)2) + Chat dien ly manh: K > 10-2 Rat can chu ST rang, hang s6 dien ly K chi c6 gia tri khong d6i va c6 (133) dung &toe cho nhung chat dien ly yeti va dung dich Wong doi bang Chat dien ly yeu d nhang n6ng dam dac hoac cac chat dien ly manh cif) K thay d6i theo n'eng Khi can phai thay the khdi niem nOng de bang hoat de ma Nhiet dung hod hoc da xay dung mei la cach khAc phut t6ng qudt nhat 1.4 Hoat cli;) va he se; hoat 1.4.1 Hoat cif; Ap dung cac tieu chuan nhiet clung cho trang thdi can bang (xem 6.3, chliong 6) thi can bAng dien ly theo pinking trinh (9-9) phai ditec vigt: K X Y a MI+ a - Ax- Z.= ([MY+ ifm,,)x fAx ([MxAY]fm \A, ) am xAy [MY+ X [A X- ])( f mX y, f AYx [MxAy] • fM A X Y 6 day, dau ( ) chi hoat de a va f la he s6 hoat dia cac eau tit Vay, co the Weil dien quan he chung giaa n6ng C va hoat de a qua he thiic: a = f C va a C (9-16) ei day, C la n6ng d6 M (mol/L), f la he s6 hoat de theo n6ng de (C cling co the thay bang n6ng d6 molan (m) hoac plidn mol (X) va f la he so hoat tticing iing voi cac loai n6ng de do) Phuong trinh (9-15) rut tii ly thuyet Nhiet clung hod hoc la t6ng quat de tinh hang S6 can bang dien ly moi trueng hop, bat luan la chat dien ly yeu hay manh, dung dich la ly thing (a do bang vo cling) hay khong 1ST ttiOng n6ng len bat 14) Tuy nhien, d cac dung dich Mang f nen a C, dung dich gan voi 1S7 -Wang, thi cac phuong trinh (9-10) den (9-14) deu ditec sii dung that -Lg Du vdy, nhling phep tinh nghiem ngat, ca voi chat dien ly yeu, n6ng nhO van phai chuyen n6ng hoat rei moi giai cac bai town ve cac tinh chat cila dung dich ei day can lien he vg ngu6n g6c cua khdi niem hoat de van dung cho dung (134) mol cilia chat i Day la dinh luat Raoult (chang 8) cho dung dich loang vo ding (1ST tuang) den mite c6 the xem i la mot chat king nguyen chat Doi -v.& dung dich thuc # X Pi') tang tac giiia cac cau tit, nhat la nhang n8ng dQ lon He dinh luat Raoult van dttOc dp dung, ngai ta phai dila them vao plittong,trinh ap suat hoi mot he s6 f dieu chinh ang dd plidn mol cho tang ling voi Pi duoc bang thuc nghiem: \= (fi X; ) Pi" (9-17) Tich s6 f.X goi la boat dQ, ky hieu bang chit a, va the hod caa cau tit i dung dich la: !A i = + RT le; /13;" = 1,1,1) + RT Infi X = 1.1;) + RT lila.; (9-18) Nhii vay, hoat dO a la dai luong duoc Sit dung de thay the cho ang dd phan mol bieu thitc hoa the, can.g nhtt cac bleu dr& nhiet dQng khdc suy tii ham hod the [vi du, bie'uthitc cac hang s6 can bang nhiet thong K, nInt hang s6 dien ly da viet d phtidng trinh (9-15)] - Mdt s6 chti ST:
+ DOI \Tad chat khi, gia thik la ly tang, a° = Pi° = atm, vi the = = P111 = Pi Dai Wong khong this nguyen vi la tS7' s6 cua hai rip suat tinh theo atm + D6i \Ted dung moi nguyen chat (16ng, ran) a° = X =-1 + Doi vdi cac chat tan a° = don vi nt'ing dQ (M, m ho‘ac X) thing thOi gia Binh la dung dich loang vo ding hay dung dich ly tang (gia dinh, vi dung dich 1M hoac lm khong the la loang vo ciing!) Cdn hieu, boat dQ cita chat tan dung dich loang vo cling bang ming di) nhung khong bang 1, do trang thdi chuSn khong thing nhat voi trang thdi ly tang (loang vo cung) + Doi \Ted tat ca cac chat ke't dm a° = = (135) va cac ion cila chat dien ly manh Co the coi hoat dO let mot n6rig coo hoat dOng - ang có hieu lit, tai no the hien tac dung 1.4.2 Hesohoatcdo Theo he that (9-16), de xac dinh hoat d6 a cila chdt ci ang C can bie't he s6 boat f - He so hoat la dai liking phan anh mot cach tang quat tat ca tucing tac cua laic tru6ng có met he Trong dung dich, f xac dinh infic dO Wong tac gifia cac phan tii va ion vdi Khi pha Mang to to dung dich, khoang cach, gicia cac lieu phan chat tan lon dan, luc Wang tac chung be, cluing chuyen deng gan hoan toan ti de bang \TO cung, cac tieu phan chat tan cach xa den mac khong tildng tac &toe vdi nhau, hoat de a clia cluing bang n6ng C, nen f = a/C = 1, dung dich dat trang thai 1ST tuang Khi n6ng chat tan tang, cac tieu phan chat tan gall nhau, tildng tac gilla cluing lon - clac biet la giiia cac ion dung dich chat dien ly manh hoac dung dich chat then ly yeu nhung dam dac Vi cac tieu phan chat tan khong dildc chuyen Ong to do, hoat tinh cua chiing giam, n6ng boat Ong a (boat do) nhO hon n6ng crO, a < C nen f = a/C < Cac chat dien ly manh dien ly hoan toan cac ion (a = 1), nhung cac ion lai khong chide hohn toan tu vi hic hap dan tinh dien gitia cluing - cac ion trai dau hilt fan de hinh nhiing cap, nhting bo ba hoac nhcing dam quyen ion dung dich Theo do, ming de tang loin, f cua cac chat dien ly giam dan, a tang be hdn C met so chat dien ly manh nitric, tang n6ng dO, he s6 hoat f di qua mot clic tieu, sau tang clan va có the f > 1, a > C Nguyen nhan la su hydrat boa manh da lam giam su hap dan ion va lam tang he s6 boat dia chat tan Nguai to goi day la hiOu zing muoi hod, lam giam hic ion (I) dia dung dich (de cap phan tiep theo), do lam tang hoat doe cila cac chat kh8ng dien ly nuOc them chat dien ly vao dung dich - He so boat de &toe xac dinh qua thuc nghiem bang each dp suat tham that] (T), de ap suat hoi (AP), dO tang nhiet soi (Ate), dO bang diem (Atd), sic dien Cac pinking phap khac deu thu dude gia tri f phu hop neu tien hanh cling dieu kien - boi vi, he so hoat chung nhfing phu thuOc vao n6ng d6 m6i chat tan ma phu thuec vao phan chung cua ca dung dich va vac) nhiet de (136) Z (9-19) + Lzfc ion W Pinking phap ly thuye't dtia khai niem laic ion I dd d'ac trun.g cho Wong tac tinh dien giiia cac ion nguoc d'au dung dich dien ly I dtioc tinh theo cong thac: I = 2 2 C 2 Z C i Z;) trong cto, Ci la n6ng d8 mol/L cua ion i Zi la dien tich cua miSi ion i I chi phu thu8c vao tang dien tich cac ion ma khong phu thu8c vao ban chat rieng cua Chung + Vi du 9.7: Tinh hic ion cila cac dung dich: a) KC1 0,010M
Gidi Ap dung phudng trinh (9-19) cho m6i truing hdp: a) I [(0,01 x 12 ) + (0,01 x 12 = 0,010
2
Lkic ion cila hiin hdp cac chat dien ly la tong cac lip ion phan Do do: I Ong I KCI ± I Na,SO4 + I MgSO4 + I salicylic 0,010 + 0,030 + 0,040 + 0,003 = 0,083 (137) laic ion dia chat dien ly 2:2 gap la'n nhti MgSO4 Laic ion cila chat dien lyy6u nhii acid salicylic ditoc tinh theo [H301 + Debye va Hiickel dila cac ding thiic tinh he s6 hoat cua tifng ion va he so- boat dO ion trung binh cUa chat dien ly Cong thiic tinh neu len moi quan he gifia he-s6 hoat dO voi laic ion cila dung dich, dien tich ciia ion, nhang dac tinh cUa dung moi va nhiet dO Can chtl y rang, he so- hoat cUct mot chat dien ly da cho la khOng thay doi cac dung dich có tang mot lu'c ion va khong phu thuiic vao bdn chat nhring chat dien ly có mat o mitt dO gido trinh nay, sau day chi neu cac truing hop van dung nhiing phiicing trinh cua Debye - Huckel, khong giai thich 1S7 thuy6t va ngu6n go,"c toan hoc cila cac phitong trinh
* He se; boat dO f, cua mot ion then tich dtioc tinh theo cong lg f; = - A Z.2 VI (9-20) A la mot he se; chi phu thuOc vao nhiet dO va hang s6 dien moi s cila dung moi: A 1,824.106 (E T)N2 Neu dung moi la nude (s = 78,5) i3 25°C thi: 1,824.106 A = 0,51 (78,5.298)3/2 va phticing trinh (9-20) vi6t lai cho dung dich rniOc la: lg = - 0,51Z,2 (9-21) (9-22) [Tinh tilting tai cho cac dung moi khac, vi du Aaceton = 3,76 (veil E = 20,70), Aethanol = 2,96 (voi c = 24,3) Lai thay cac he s6 A vao phtiong trinh (9-20) d6 dude each tinh moi dung moi do] * He s6 boat dO ion trung binh f± cua mot chat dien ly tinh theo cong thiic: (138) A Z(,Z( _, 1g f, = (9-26) Ky hieu Z(+), bigu thi dien tich cac ion phan tii chat dien ly (khong vik Z;2 nhv cong thfic (9-20) vi c6 thg Z(0 # Zo) Trong dung dich nvoc thi: lg f+ = - 0,51 Z(+, Zo Aff (9-24) + VI du 9.8: Tinh he s6 hoat va hoat ion trung binh dung dich ntidc cua thu6c atropin sulfat 0,005M (At = C171-123%N.H2SO4.H20 = 694,8, thu6c lam gian cd trcin, gian clang tii, thong co that, cat hen) va co mat clang thai NaC1 0,01M d 25°C Gicii Thu6c At la chat dien ly 1:2 nen Z(+).Zo = x = 2, I At 2 (0,005 X x12 ) + (0,005 x 22 )] = 0,015 I NaCI 40,01 X 12 ) (0,01 X 12 )1 = 0,01 2 Ito'ng = 0,025 Ap dung cong thfic (9-24): lg f+ = - 0,51x x V0,025 f+ = 0,690 va aAt = 0,690 x 0,005 = 0,0035 Day chinh la nang hoat clang c6 hieu laic cua thu6c Chu S7 rang, mac du laic ion la tang laic cua tat ca cac ion c6 mat dimg dich, nhiing Z(.0.Z0 la ciia thu6c can xac dinh he s6 hoat nen phai dva tich s6 vao phlking trinh (9-24)
lg f; = A Z.2 -J (9-25) 1 + R i l3Aff (139) trong do, B la hang so chi phu thuec nhiet va hang so dien mOi s (gi6ng nhu A), Ri la ban kinh ion hydrat dm ion i Trong dung dich nude nguai ta xac dinh duoc 11;13 1, nen: lg fi lg f, = 0,51z i 2-11 ± 0,51 Z(±) Z( _oil-1 + (9-27) (9-28)
A Z(, " Z lg f+ = + C, (9-29) 1 + R i B VI C1 la hang s6 kinh nghiem chtta ro ban chat va each tinh CI luon luon during, có the lem hon s6 hang am cila pinking trinh, f > + Vi du 9.9: Tinh he s6 hoat va boat trung binh dung dich nude cua Na phenolbarbital 0,004M (NaC1211111\1203 = 254,24, thu6c an than, gay nga, gian co) a 25°C Dung dich thu6c da dtiOc pha them NaC1 de cólUc ion 0,09 Gidi Vi I = 0,09 nen dp dung cong thilc (9-28) va thu6c dien ly 1:1 nen Zeo.Zo = x = 1, vay: 0,51 x x x '09 = 0,76 1g f+ = • + V0,09 atha-c = 0,76 x 0,004 = 0,003 (140) 136ng 9.3 HO s6 hoat d() (f,) cua mot s6 ion co diOn tich khac cac dung dich co li/c ion I bier) d6i Lcrc ion (I) ciia dung dich He so hoat dO f, Ion dien tich (1±) Ion dien tich (2±) Ion dientich (3±) 0,0000 1 0,0001 0,99 0,95 0,90 0,001 0,96 0,87 0,72 0,002 0,95 0,81 0,63 0,005 0,92 0,72 0,48 0,01 0,89 0,63 0,35 0,02 0,87 0,57 0,28 0,05 0,81 0,43 0,15 0,1 0,76 0,33 0,08 0,2 0,70 0.24 0,04 0,5 0,62 0,15 0,014 + VI du 9.10: TInh he s6 hoat \Ta boat cua cac ion Al' va S042-trong dung dich nu& Al2(SO4)3 0,007M Gidi Nhom sulfat la chgt dien ly manh dien ly hoan toan = 1), nen: CAS ,, Cso:- = \= 0,007 x 0,007 x \= = 0,0140 mol/L 0,0210 mol/L Theo phudng trinh (9-19) thi: -40 ,014x 32 )+(0,021x 2 )1 0,1 Tra bang 9.3 luc ion 0,1, dtioc fAi ,„ = 0,08 va I.50,2_= 0,33, vay hoat dO: a Al, * a so -, , \= = 0,08 x 0,0140 0,33 x 0,0210 \= = 0,0011 (141) fret qua cho thay, boat dO cua A13+ nhO hdn neing d6 — 13 loin, dm S042- la — loin 2 THUYET ACID - BASE 2.1 Thuygt Arrhenius (thuygt clien ly H+, OH-) Nam 1884 nha hod hoc Thuy Dien Svante Arrhenius (1859 1927) dila thuyet dien ly cua cac chat, có dinh nghia acid - base: Acid la nhfing chat chlia hydro va có the dien ly nu6c tao ion H+ (viet dung la H30+) Base la nhiing chat chila nhom OH va có the dien ly nu6c tao ion hydroxyl OH- Phan Ting gilia acid ya base goi la phdn zing trung hod, la ski ke't hop gifia cac ion H+ va OH- tao H2O rat it dien ly: H+ (aq) + OH- (aq) > H2O (1) Afep)u = -55,9 kJ (9-30) Mu6i la san pha.'m cUa phan iing trung hoa ding voi nu6c Thuyet cila Arrhenius coy nghia 16n hoa hoc No giai thich duoc cac tinh chat chung cua cac acid: Phan iing v6i base tao muoi va mi6c; Phan ling veil mot s6kim loci cho hydro thoat ra; Lam bien d6i m.au cua cac chat chi thi (vi du, lam quY c6 mau c16); CO vi chua, bai vi nu6c, cac acid cte'u dien ly ion chung la H30+ Thong tti, base dUoc dac tning bai cac tinh chat chung: Phan ling veil acid tao mu6i; Lam bien d6i mau cac chat chi thi, khac voi mau acid lam bien d6i (vi du, lam cho quY có mau xanh); CO vi "xa phong" d4c trung, bai vi nuoc, cac base deu dien ly ion chung la OH- Tuy nhien, thuyet Arrhenius có nhieu han che, chi dung moi truang nu6c cho nhieu chat Vi chua neu duoc vai trO cUa dung moi nen có nhfing chat khong chiia nhom OH nhung von có tinh base (nhii NH3, cac amin him cd, cac mu6i KCN, NaCH3C00, Na2S ), ho4c chat khong (142) Nf1,3 (k) + HC1 (k) NH,,C1 (r) Ro rang, khdi niQm vg acid - base can c6 mot 1S7 thuygt tang qudt hon 2.2 Thuygt Bronsted - Lowry (thuygt proton) — Nam 1923, nha hod hoc Dan Mach J.N Bronsted (1879 - 1947) va nha hod hoc Anh T Lowry (1874 - 1936) tong ctiia mot 1S7 thuygt rQng hdn vg acid - base, goi la thuygt Bronsted - Lowry: Acid la mot phAn tit (phan tit, ion) c6 th6 cho mot proton H Base la mot phAn tit (phan tit, ion) c6 the nhAn mot proton H+ Base phai c6 mot cap electron to de lien k6t vdi mot ion W KST hi:0 HA la mot acid, no cho mot proton theo phdn HA H+ + A- (9-31) Theo chigu nghich, A- nha.n mot proton se cho lai HA, d6 A- mot base Ngttai ta not HA I A- let mot cap acid - base lien hop Ky hieu B IA mot base, no nhAn mot proton theo phan B + BH± (9-32) Khi BH+ cho mot proton, no dong vai tr6 mot acid va tao lai B Ngt,thi ta not RH+ I B la mot cap acid - base lien hop Chit51: + Acid lam vigt ben trdi net gach nghieng, base luon ben phai + M6i cap acid - base lien hop chi trao dOi (cho - nhdn) proton (chdt c6 thg cho - nhdn nhigu proton thi se tao nhigu cap lien hop) + Cdc chdt acid theo Arrhenius van dung thuygt Bronsted - Lowry, vi cluing van diQn ly (cho) ion H+ (proton) Nhung base Bronsted - Lowry thi khong nhdt thigt phai c6 nhom OH nhu base Arrhenius Ban than ion OW la mot base vi c6 thg nhdn proton • Thuygt Bronsted - Lowry &An mot s6 hQ qua: DQ manh tildng ctOi cua mot acid hay mot base duoc bdi xu twang 6' hay kho chUng cho hay nham proton HC1 la mot acid manh nudc bdi vi no cho di proton dg dang, CH,COOH la mot acid ygu bdi vi chi cho proton d mite dQ n11.6 (143) amoniac fang; HC1 la acid manh rat& nhung la acid yeu dung moi acid acetic bang; anilin la mot base nttcic, ntning la mot acid yeu amoniac long Nhu vay, dO manh cua mot acid khong chi phu thuOc vao kha nang cho proton ciia no, ma phu thuOc vao kha nang dung moi nhan proton tit acid Kha nang duoc goi la manh base ciia dung moi Theo do, dung moi &toe phan cac loai:
- Dva vao dinh nghia thi acid va base có thg la anion nhu HSO4, HCO3-, CH3C00-, CN-, OH-; cation nhu H30+, NH4+, Bi(OH)2+; phan tit trung hoa nhU H20, NH3, HC1, CH3COOH - Vi proton khong trang thai tit do, nen mot chgt cho mot proton thi phai có mot chgt khac nhan no Do do, mot phdn zing acid - base thu'c chat let mot qua trinh van chuye'n proton giica cap acid - base lien hdp Dieu nay dtioc the hien qua so del: Al + B2 -'= - A2 + B1 (9-33) acidl base2 acid basel Phan ling có lien quan dgn cap acid - base lien hop Al/B1 va A2/B2 Chigu xay cua phan -tang acid - base phu thuOc vao de manh Wong doi ciia acid va cila base Wong tac Nguyen t6.'c chung nhat disc rut ra: phdn (mg xdy theo chi& acid manh han tdc dung ()di base manh han Bang (144) KhOng Bang 1Ce Rift ye'u You Trung Binh Manh Bing 9.4 DO manh cua mot s6 cap acid - base lien hdp (acid manh nhat xep tren clung ben trai, base manh nhat xep du'di ceing ben phai) ACID HO H ,SD, Mkt nh H NO, H,00+ HSO, Trung H290, bi nh H PO., H F CH,C00 H H,00, H ,S H H PO,' N H4+ HOD, Rat y6u H PO: H 20 Khong HS ding ke OH Tif bang 9.4 c6 the nhan xet: BASE -> H ' -> H HSO, - H' NO, H' + H,0 H ' + 90 4' H' + HSO, H H, PO, H + F H + C1-1 ,C00 H + HCO, H' + HS H' + SO' H + HPO: H' + NH, H + CO 3' H ' + FO H + OH H' + H' 02 , u
H2S + NH3 HS- + NH4 (9-33a) acid1 base2 base acid manh hdn manh hdn yeu 'hdn yeu hdn Co the xem phan ling tranh chap proton gifia NH3 va SH-, NH, la base manh hdn nen da thang, phan ling chuyen manh sang ben phai HNO„ + H2O -I,- NO3- + H30+ (9-33b) acid' base2 base acid manh hdn manh bon ' y6u hon yeu hdn (145) HF + H2O -` .='' F- + H30+ (9-33c) acid1 base2 ii base acid manh hdn manh hon yeu hon yeti hdn HF la acid yeu hdn H30+, nen nu& chi yeti ten tai cac phan ti HF khong dien ly Phan ling (9-33c) chuyen manh sang ben trai Theo nghia rOng, cac phan iing trung hoa, thug phan hay trao doi deu có the mo to theo phuong trinh (9-33), nhu cac vi duo bang 9.5 Bang 9.5 Cac loai ph5n Ong acid - base Phan Ting Acid Base Acid Base Trung hoa H30+ + OH - H20 + H,0 Trung hoa Trung hoa NI-14+ HC1 OH- + NH, Cl - + H2O + NI-13 NH4+ + Thug phan H2O + CH3COO CH3COOH + OH- Thus' phan NH4+ + H2O H30+ + NH3 Trao d6i HC1 + CN - HCN + Cl Thuyet proton ciia Bronsted - Lowry v6 acid - base la 1s' thuyet hien dai va hoan chinh, duoc van dung rOng rai hod hoc hien Su xem xet dinh tinh, dinh Wong cac trang thai can bang tiep theo chuOng deli dua tren khai niem acid - base cila ly thuyet dO nhting chi gidi han dung moi 2.3 Thuyet Lewis (thuyet electron) Khi xet moi quan he v6 eau trot electron cita cac phan ti'i acid, base su hinh lien ket Ong hod tri kieu phOi tri, cang nam 1923, nha hod hoc nguai My G.N Lewis (1875 - 1946) dua dinh nghia: Acid mot phdn tip nhdn mot cap electron di tcto mot lien ket tong hod tri Base mot phdn cho mot cap electron try cle' lien ket vdi acid Nhu vay, doi \Ted base thi dinh nghia cila Lewis va cua Bronsted - Lowry la nhu vi deu doi hOi base phai cap electron tu Su khac co ban gifiia hai thuyet la doi vdi acid Thuyet electron cilia Lewis khong doi hoi cac phan tif acid nhat thiet phai chita H de cho proton nhu 6 thuyet Bronsted -Lowry, do khai quat hon Thiic chat thi acid nhieng chdt có orbital hod (146) + VI du 9.11: Cac phan ling diidi day la minh hop cho thuy'et Lewis - Phan iing trung hoh: H+ + :0:11 H2O acid base Vay, proton (H+) mot acid - Phan ling gitia cac phan tit Acid Base F H F-13 • :N-H F3B-14-13 Cl F H CH3 Cl -Al • :0 C13A1 0(CH3)2 Cl CH3 AlC13 • CH3C1 CH3+C6H6 + [C1A1C13] benzen (-) ± : 6 H ,3 (_) y (+) 0=C0 + : (15: Ca2+ • • - Phan iing k'et hop: BC13 + BC14 H + :NH3 NI-14+ - Phan ling tao pink dung dich midc: Cu 2+ (aq) + (:NH3)4 {Cu (NH3)4] 2+ + aq - Phan Ting thug phan: AC+ + AlOH 2+ H H CH3+[C1A1C13] C6H5CH3 + toluen A1C13 + HC1 OH O=S' OH - :0: - 2- (147) Thuyet Lewis cho phep hien sau lion co the phan -ling acid - base Nhung vi qua rOng nen no khong có kha nang dita phep dinh lttOng ve cliang dO acid Thuyet Lewis hau nhit chi thuan tien cho phan loci electron cau tao chat Ngay viec dOi hoi cac phan tit HC1, HNO3, H2SO4 phai nhan cap electron moi coi la acid thi that la mot dieu khien citEing 3 S15 HIEN LY CUA THANG PH CUA SORENSEN 3.1 Ski dien ly caa 'nide Nu& la dung moi Wang tinh, vita cho Ira vita nhan proton: H2O + OH- (9-34) H20 + H+ H30+ (9-35) H2O + H2O H30÷ + OH- (9-36) acid base acid base va -Wong vdi cap acid - base lien hop theo thuyeI Bronsted - Lowry: H20/0H- va 1-130+/H20 Mac du su dien ly cua nude rat be, nguai to van duoc dO d'an dien cUa no va xac dinh ditoc gia tri cUa hang s6 can bang cila phuong trinh (9-36) theo dinh luat tac dung kh6i Wong: [H,01 [OH- ] K = = 3,24.10-'8 (6 25°C) (9-37) [H 0]2 K [H20}2 = 3,24.10' (1000 )2 = Kn = [H301 [OH-] = 1,0.10'4 (9-38) 18 (mOt cach chat the thi phai viet cac n6ng dO [ cac hoat de a H„ a oH _ , a.,0 khong this nguyen, vi dieu kien chua.'n da so sanh vdi cac hoat di) chua'n = mol/L Theo do, phuong trinh (9-38) phai dudc viet la: a H x a0- F1 = 1,0 X 10 14 (9-39) Hang so K„goi la tich s6 ion ciia rutoc Tich s6 thay d6i theo nhiet de Vi mot ion H30+ va mot ion OH- ditoc phan ly tit mot phan tit H2O, do nttdc nguyen chA: [H30+] = [01-1-] = V10-14 = 10' mol/L (9-40) 1000 (148) tip rill& chi c6 phan tii dien ly cac ion) Dua vao can bang dien ly cUa nu6c, ngtidi ta dinh nghia dung dich acid, base va trung tinh tuST theo d6 lon WI:Mg do-i gicia [H301 va Dung dich Gidi flan chung O 25°C Acid [H301 > [OH-] [H301 > 10-7 [OH-] < 10-7 Trung tinh [H301 = [OH-] [H301 = 10-7 [OH-] = 10-7 Base [H301 < [OH-] [H301 < 10-7 [OH] > 10-7 Vi Kn la hang sod nhiet d6 nhat dinh, nen biet n6ng d6 cua mot hai ion, ta có the tinh &foe n6ng d6 ion + VI du 9.12: Biet n6ng [H301cua mot dung dich bang 3,0.10-4M Tinh [OH-] va cho biet dung dich la acid, trung tinh hay base? Gidi 10-'4 [H 301 3,0x10-4 Day la dung dich acid vi [H301 > [OH-] 3.2 Thang pH [OH] = = 3,3 x 10-11 M I\TOng d6 H30+ dung dich nvoc c6 the Wen d6i tren mot pham vi Ong tfi 10M den 101°M, gay kilo khan va dai &mg tinh toan, do Sorensen de nghi dung dai laic ng pH a bieu thi ti6m nang ion hydro (hydrogen ion potential) v6i dinh nghia: pH = -1g [H301 hoac [H301 = 10-"11 (9-41) va pOH = -1g [OH-] hoac [OH-] = 10-"°H (9-42) Vi Kn = [H301 [OH-1 = 1,0 x 10-14 nen ng-U6i ta cung hay dung dai Wong: pKn = -1gKn = -1g[H,01 [OW] = -1g[H301 - lg[011+] = pH + pOH = 14 (9-43) (6 25°C) (149) Bang 9.6 Quan he giCia [H301 ], pH, pOH va [OH7 [11,04 ] pH pOH [OH] 10j5 1014 10" 1 0- 10-" o b" 10 -9 108 lo 10 10 10 -4 10' 102 10-' 1 10' 15 14 — 13 — 19 — 11 — 10- 9- 8- 7-6— 5— — 3 — — 1 — 0 1— (o "LI b.0 <o O <0 *ti I raP ,c) -1 - - 1 — — — — — — — — — 10 — 11 — 12 — 13 —14 15 10' 10' 10 10-1 10-4 10 10 10-7 10 10 10 " 10" 10 12 10" 10'4 10'5 tO >ct <0 Trung b0 ict M c) <0 Ci=1 thin - Chzi a) Vi phu thu6c nhiet d6 nen pK„, pH, pOH cua nit& nguyen chgt cling thay d6i theo nhiet (bang 9.7) Bang 9.7 Tich s6 ion (Kr) cua nutic nguyen chat a mot s6 nhiet c16 Nhiet (°C) lc x 10' pKn pH = pOH 0 0,11 14,96 7,48 10 0,29 14,54 7,27 25 1,00 14,00 7,00 50 5,66 13,25 6,62 100 51,30 12,29 6,15 300 400,00 11,40 5,70
pH = -1ga., (9-44) a = f± C = f± [H301 = He se- hoat d6 x N6ng d6 ion hydro + Vi du 9.13: (150) NaOH 1M (14,0) Dich giat (13,0) Amoniac gia dung (11,9) 1 NInTi dich MgO china N dau da day (10,5) Dung dich rira (ung, mun, vet filming) (-10,0) Nu& bin (7,0 - 8,3) Mau (7,4) TRUNG TINH SCra (6,4) Nuoc tieu (4,8 - 7,5) NuOc mua sach (5,6) Bia u6ng (4,0 - 4,5) Darn chua (2,4 - 3,4) Nude chanh vat (2,2 - 2,4) Dich da day (1,0 - 3,0) HC1 IM (0,0) 10 9 pH
Gidi
- Hinh 9.1 cho biet pH dm met s6 dung dich niiOc thliang g4p (151) 4 CAN BANG ACID - BASE 4.1 Sif dien ly caa cac acid ygu Trong nu6c, acid yki HA di6n ly qua phan itng voi phan tit H2O: HA + H2O H30+ + A- (9-45) Theo dinh luat tac dung kh6i Wong, hang s6 can bang cila phan fing ducic vik: [Hi0+ ] [A] K = - (9-46) [HA] [H20] Doi v6i dung dich loang va cho muc dich thuc hanh, ngithi ta coi lacing niidc la du lon de duoc xem la hang s6 ([H20] lit nueic 25°C vao khoang 55,5 mol/L) Tit do, phuong trinh (9-46) ditoc bien d6i: K [H2 O] = Kd =[H2O A]] (9-47) [H Ka goi la hang s6di6n ly acid, citing goi la hang s6 acid Nguai ta dung dai Wong: pKa = -1g Ka (9-48) va goi la chi s6 sift acid Gia tri Ka va pKa the hien d6 manh - 376u cua mot acid Ka cang 16n, acid cang manh, vi ii trang thai can bang no di6n ly duoc nhieu hon ion hydroni H30+ dung dich va ngvoc lai Neu danh gia theo pKa thi, acid cang manh pKa cang nhO va ngtfcic Chzi neu HA la acid manh, chang han nhu HNO3, din ly hoan toan nitoc, the la nitric thau tom tat ca proton cUa acid: HNO3 + H2O —> H30+ + NO3- thi [HA] lac can bang = [HNO3]],„an Wang trang thai can bang khong ton tai cac phan tit acid khong di6n ly, phan ifng hoan than mot chi6u, Ka tr6 nen lon vo cling, do no khong ditoc icac dinh dieu ki-en thong thuOng (152) Bang 9.8 Gia tri Ka di' a mot s6 acid don chdc 6 25°C Ten Cong t h Lic Ka Acid iodic HIO, 1,6 x 10-1 Acid cloro HC102 1,1 x 10' r-, I 1 -' DO ma n h ac id tang Acid nitro HNO2 7,1 x 10' Acid hydrofluoric HF 6,8 x 10-4 Acid acetyl salicylic (aspirin) CH3000C6H4COOH 3,27 x 10' Acid benzoic C6H5COOH 6,3 x 10-5 Acid acetic CH3COOH 1,8 x 10-5 Acid propanoic CH3CH2COOH 1,3 x 10-5 Sulfacetamid C81-1,0N203S 1,35 x 10-6 Sulfadiazin C1oH1oN402S 3,3 x 10' Acid hypocloro HCIO 2,9 x 10' Pentobarbital C111-118N203 1,0 x 10' Acid hypobromo HBrO 2,3 x 10-9 Acid hydrocyanic HCN 6,2 x 10-1° Phenol C61-150H 1,0 x 10-19 Acetaminophen (paracetamol) C81-19NO2 1,1 x 10'9 Acid iodo HIO 2,3 x 10-11 4.2 S4 (WO ly cita cac base ygu - Base yeu B dung dich nuoc có phan ling: B + H2O BH+ + OH- a day, thuyk Bronsted - Lowry liiu ST rang, base B phai có cap electron tai de ket hop (thau torn) proton dm phan tii niidc, do tao mot n6ng d(5 OH- dung dich Base Bronsted - Lowry khong nhat thiet phai chlia san nhom OH cau tao cilia no Phan ling (9-49) có hang so can bang: [BH± ] [OH ] K = xem [H20] = const thi: [B] [H 0] - K[H 0] = Kb = [BH± ] [OH ] [B] Kb goi la hang s6 dien ly base, cling goi la hang s6 base (153) K b — [NH,] = 1,76 x 10-5 (a 25°C) [NH 4+ ] [OFF] Ngttdi to cling dung dai pKb = - lg Kb (9-51) va goi la chi s6 sic base Kb cang Ion, hay pKb cang nh6, base cang manh va ngt lc lai Chit toan be Wong base manh, chang han nhtt NaOH, c6 mat dung dich dgu thau tern proton ci:ia nUoc: NaOH + 1130+ Na+ + 2H2 phan Ung met chigu, nen cling nhu doi voi acid manh, Kb Ion ve ding va khong duoc xac dinh digu kien thong thtiOng — Met base phan tit quen thuec la NH3, nit& no c6 phan ling: :NH3 + H2O NH4+ + OH - Do Kb nh6 nen nuoc ten tai chu ygu cac phan tit NH3 (mac du tren nhan lo hoa chat van ghi la "amoni hydroxyd") Trong dung dich cac base ygu g6m nhom lon: + Base phan tit trung hoa, nhu amoniac, cac amin him co + Base ion gem tat ca cac anion dm cac acid y6u Bang 9.9 ghi gia tri Kb ciia met so base phan tit trung hoa (nhom amin) Bing 9.9 Gia tri Kb caa mot s6 base phan tit nhOm amin Ten Cong thitc Kb Diethylamin (CH3CH2)2NH 8,6 x 10' Dimethylamin (CH3)2NH 5,9 x 10-4 ma nh bas e t ang Trimethylamin (CH3)3N 5,2 x 10-4 Methylamin CH3NH2 4,4 x 10-4 Ethanolamin HOCH2CH2NH2 5,0 x 10-5 Atropin C171 123NO3 4,5 x 10-5 Codein C181 121NO3 1,6 x 10-6 Amoniac NH3 1,76 x 10-5 Pyridin C5H5N 1,7 x 10-9 Anilin C6H5NH2 4,0 x 10-19 (154) 4.3 Quan he giiia Ka va Kb cira mot cap acid - base lien hcip Co mot moi quan he don gian ma quan gift-a hang s6 dien ly cua mot acid yeti (HA) va cila base lien hop cila no (A-) dung med Wong tinh nhit nttcic Quan he ditoc nhan qua cac phtiong trinh: HA + H2O H30+ + A Ka = [H30+] [Al [HA] A - + H2O HA + OH- Kb = [HA] [OH-] [A-] Ka x Kb = [H30 ± [A] x [HA] [0H- ] ;0+ 1[0H- 1= K (9-52) [HA] [Al a 25°C, Ka x Kb = K„ = 1,0 x 10' (9-53) M6i quan he cho phep tim ditoc Ka neu biet Kb, va ngitoc lai Liu S7 rang, cac bang tra citu, ngtiai ta chi ghi cac gia tri K va Kb cua phan tip acid va base trung hoa Mu6n biet Kb, vi du cua CN- va Ka, vi du dia CH3NH3+, thi sit dung phitong trinh (9-53) Sau tra bang, ditoc biet Ka (HCN) = 6,2 x 10' thi: Kb (CN-) 1,0 x10 14 1,0 X10-14 6,2 x10-1() = 1,6 x 10-5 K a (HCN) va biet Kb (CH3NH2) = 4,4 x10-4 thi: 1,0x10 14 1,0x10 14 = K = 2,3 x 1011 a (Ltiv,n3+) je 4,4 x 10 " b (CH 31\11-12 ) 4.4 Su dien ly cita acid, base da chic Chgt Wang tinh — Cac plidn tren moi de cap den acid, base don chitc - phan tit chat chi cho hoac nhan proton Neu mol chat có the cho hoac nhan tit proton tra len, ta goi nhfing chat la acid hoac base da chic — Acid da chat dien ly tieng nac, moi nac cho proton Vi du, acid phosphoric có 3 chic acid dien ly theo phan itng nac: 1/ H3PO4 + H2O H30+ H2PO4 [H301 [H2PO4 \= 7,5 x 10-3 va pKai = -1g Kai = 2,1 [H,PO4 ] (155) 2/ H2PO4 + H2O H30+ + HP042- [F130+ 1[HP0 Ka = 6,2 x10-8 va plc" = -1g Ka, = 7,2 3/ HP042- + H2O H30-1- + P043 [F130+ ][PO 4' ] \= 3,6x10-13 va = -1g Ka, = 12,4 [HP0 42- ] Phan Ung dien ly tang Ong: H3PO4 + H2O H30+ + P043- [H3013 [ P043 ] \= Kal Ka2 Ka3 = 17x10-22 [H3PO4 ] va pKa = - lg Ka tong = pKa, + pKa + pKa, = 21,7 tong Ka , Ka, , Ka, goi la cac hang so- diet' ly nac pK , , pKa la cac chi s6 sic acid nac Ka , pKa la hang s6 dien ly tang cong va chi s6 sic acid tong cong Tit cac phan ing dien ly cua H3PO4, rut cac nhan xet chung: + Hang s6 dien ly nac Ion hdn nhieu so \Ted nac Dac biet Ka, vO cimg be, den mic có the xem thuc to la khong ton tai ion PO4' dung dich Noi chung, neu Ka >> Ka, thi cac phep tinh gan dung nguai to chi sit dung tri so- dm Ka , acid da chic ctuoc coi la don chile + Hang s6 dien ly tang cong bang tich cac hang so- dien ly nac pK tang cong bang tong cac pK nac + Ion PO,' chinh la mat base da chic va ming nhan proton theo nac, m8i nac chi nhan proton tit phan tif nude nhu cac phan ing sau: 1/ P043- + H2O HP042- + OH- [11 PO K a, Ka (156) K r, 1,0 x10-14 Ka, 3,6 x 10-1 = 2,8 x 10-2 K = b [P0431 [OH-1[HP042- ] pKb, = -1g K b = 1,6 day the hien m6i quan he cila cap acid - base lien hop HP042-/P043- 2/ HP042- + H2O H2PO4 + OH - Kb, [OH- ] [H2 P041 K r, 1,0 x 10-14 [HP0421 Ka, 6,2 x10-8 \= 1,6 x 10-7 pK b, = -lg K b2 = 6,8 ei day 1a the hien m6i quan he cim cap acid-base lien hdp H2P0,,-/HP0 3/ H2PO4 + H2O [OHl[HiPO4] [H2 PO4 H3PO4 + OH K 1,0 x10-14 \= 1,3 x 10-12 K a 7,5 x10-3 Kb, pK b; = -lg = 11,9 day the hien m6i quan he cila cap acid- base lien hop H3PO4/H2PO4- VA phan iing dien ly base tong Ong: P043- + H2O OH - + H3PO4 [OH13 [H3PO4 ] 5,8 x 10-21 \= Kbi Kb, • K b; Kb iOng [P043-] va pK btcmg = -1g = pK b, + pK b, + pK b, = 20,3 — Nhii vay, mot acid da eh& HnA sau cho di tat ca proton se tao mot base da chfic n cap acid - base lien hop O vi du H3PO4 to thgy có cap acid - base lien hdp va cac m6i quan he gitia chung thioc nhan là: Ka x Kb = Ka2 x Kb2 = Ka X Kb = K,, = 1,0 x 10-14 K„ x Kb = Kai x Ka, x Ka x Kb] X K b2 x Kb3 = Kn3 = 10-4' uing tong (157) - Bang 9.10 cho bie't hang s6 dien ly ciia mot s6 acid da chic Bang 9.10 Hang s6 diOn ly co a mot s6 acid da chat Ten Cong that Ka l Ka Ka Acid oxalic 1-12C204 5,6 x 10-2 5,4 x 10-5 Acid phosphors H3P03 3,0 x 10-2 1,7 x 10-7 Acid sulfurs H2S03 1,4 x 10' 6;5 x 10' flo man n ac id t ang Acid phosphoric 1-13PO4 7,5 x 10' 6,2 x 10 3,6 x 1013 Acid arsenic 1-13As04 6,0 x 10" 1,1 x 10-7 3,0 x 10-12 Acid citric C61-1807 7,5 x 10-4 1,7 x 10-5 4,0 x 10-2 Tetracyclin C221-124N208 5,0 x 10-4 2,1 x 10' 2,0 x 10-1° Acid ascorbic C6 -1806 5,0 x 10-5 1,6 x 10-12 (Vitamin C) Acid carbonic I H2CO3 4,5 x 10-7 4,7 x 10-1' Acid hydrosuifuric H2S 9,0 x 10-8 1,0 x 10-17 - Chat luThig tinh O vi du di:0 ly cila acid phosphoric, cac ion H2PO4- va HP042- c6 th4 c6 chic nang caa mot acid hay cila mot base Nhin chung, he acid da chic H„A, tat ca cac ion d6u c6 chic nang nhU the, frit H„A va MO1 ion có the' dOng vai trb nhu' mot acid hay mot base du'o'c goi la chdt tinh Cac acid amin va protein la nhung chat hiong tinh duoc quan tam dac biet Duoc hoc Vi du, glycin (H2NCH2COOH), la mot acid amin c6 phdn cac dung dich dam a tiem truy6n, hoac pha dung dich d4 riia phau thuat Glycin boat tong nhu mot acid hoac mot base: +NH3CH2C00 + H2O NH2CH2C00- + H30+ +NH3CH2C00 + H2O ± NH3CH2COOH + OH- Cau tit +NH3CH2C00- goi la phan try ion, no mang ca din tIch duong va (158) 4.5 Cach tinh pH 'mit se; dung dich Dua vao pinking trinh bao toan neng do, phuong trinh bao toan dien tich va cac hang s6 can bang, nguai ta co the tinh chinh xac [H301, to tinh pH cho moi dung dich co phan bat 1(57 Tuy nhien, nhieu he phuong trinh rat phfic tap, kilo giai; hon nfia, gia tri pH qua chinh xac v6i nhieu s6 le sau hang ddn vi ciing la dieu khong can thiet Trong thiic to nguai ta chap nhan cach tinh gan thing ma van thoa man cac gi6i han sai se duoc &at cho tang truOng hop cu the A Dung dich acid manh, base manh - Tinh pH ceza dung dich acid manh ddn chac: Acid manh HA, n6ng Ca mol/L, dttoc xem la dien ly hoan toan (a = 1) dung dich /Woe Cac can bang then ly tao n6ng chua biet [H301, [OH-] va [Al nen can pinking trinh dec lap lien quan de xac Binh: • HA + H2O 1130+ + A- (a) H2O + H2O H30+ + OH- (b) [11301 = + [OH-] (c) Can di phuong trinh bao toan dien tich (c) va tich s6 n6ng ion cua nuoc theo (b) ta tinh thioc: [H30+] = Ca + Kn (9-54) [H301 Giai phuong trinh bac 2: [H30-12 - Ca[H30+] - Kn = tim [H30-1 rei to tinh pH Day la phuong trinh &toe ap dung cho bat kS7 met acid manh nao vdi n6ng Ca tuS7 S7 Neu Ca 1,12.10' M (nghia la chap nhan dung dich acid có pH :5_ 6,95, each biet 5% don vi pH so voi gidi han trung tinh) thi b6 qua [H301 nudc dien ly ra, do [H301 = Ca va: pH = -1gCa (9-55) Cita )5: Neu dung dich gem chlia nhieu acid manh don chile HA, n6ng d6 Cal, HA2 n6ng Ca2 thi Ca (9-54) la tong n6ng cac acid co mat: Ca = Cal + Ca2 + + VI du 9.14: Tinh [H30+] va pH cac dung dich: a) HNO3 0,015 M ; b) HC1 10-7M va c) gem HNO3 0,0100M va HC1 0,0015M Gidi (159)
1,6.10-7M va pH = -1g(1,6.10 7) = 6,80
- Tinh pH cUa dung dich base manh dan chic: Base manh BOH, nOng dQ Cb mol/L, dien ly hoan than dung dich ntidc Bang each giang nhtt dai voi acid manh, xet phtiong trinh dQc lap: BOH 2H20 [OH-] OH- + 13+ OH- + H30+ [B+] + [1130+] Rat ra: Kn [OH-] = Cb + hay [H301+ Cb = (9-56) [O Kn H1 [H301 Giai phttong trinh bac hai tim dttoc [OW] hoac [H301, tit tinh pH ciia dung dich Neu Cb 1,12.10 7M thi be) qua [OH-] nuoc dien ly (nghia la chap nhan dung dich base c6 pH ?_ 7,05, each biet 5% don vi pH so veil gioi han trung tinh), do [OW] = Cb va: pH = 14 + 1gCb (9-57) Neil dung dich gam chita nhieu base manh thi Cb la tang nang cac base có mat + Vi du 9.15: Tinh pH cac dung dich: a) NaOH 0,5M; b) CsOH 10-7M va c) gam NaOH 0,5M va CsOH 0,3M Gidi
1,6.10-7M = pOH = 6,80 nen pH = 14 - 6,80 = 7,20
(160) + Nuking trinh dien ly cila acid yeti HA có n6ng ban dau Ca va hang s6 can bang Ka: HA + H2O H3 0+ + A- Ka - [H30± ][A] [HA] + Phuong trinh dien ly cua nude: H2O + H2O H30+ + OH- Kn = [11,04] [OW] = 10' + Plationg trinh bao toan n6ng dd, vdi Cb la n6ng dd ban dau cila base yeu lien hdp A-: Ca + Cb = [HA] + [A-] + Phtiong trinh bao than dien tich: [H30+] = [A-] + [OW] Sau to hdp pinking trinh tren va sap xe-p lai, thu duoc: (Ca - [H30+ ] + [OW]) [H30+] = Ka (9-58) (Cb + [H30+ ] - [OW]) Day la pinking trinh chinh xac va tang quest, có the trien khai tinh town ma khOng can kem then bat kS7 gia thiet nao Phtiong trinh (9-58) duoc ap dung de tinh pH cho nhieu truang hop cu the - Tinh pH cua dung dich mot acid yeu don Dung dich chi chiia met acid yeu nen Cb = 0, thay [OW] = Kn va sdp.xep lai, pinking trinh (9-58) tr6 thanh: Ca [H3012 - Kn [H3012 - Kn [H30+ ] (9-59) Phtiong trinh (9-59) cho phep tinh [H301, tit tinh pH chinh xac cho bat kST dung dich nao chiia mot acid yeu nude De tinh gan dung nguai- to chap nhan sai s6 < 5% (goi la gia thiet 5%): mot gia tri < 5% so vdi mot gia tri khac thi có the 136 qua Van dung gia thiet 5% a xet (9-59) cho thay, nein (Kn/[H3012) < 5%, nghia la [H30+] > 4,47.10-7M thi b6 qua [H30+] nit& dien ly ra, do phtidng trinh (9-59) tra thanh: [H30÷ ] (161) [H3012 Ca - [F1301 Neu ([14301/Ca) < 5% thi (9-60) dude thu gon lai: [H3012 Ka = [H301 = A/Ka Ca (9-61) Ca 6 day can hieu, doi h6i Ca du ion nhung Ka cung phai du nhO de [H301 tii acid dien ly c6 the b6 qua Van dung gia thiet 5%, ta c6 tieu chi don gian de alp dung (9-61) la Ca > 400 Ka + Vi du 9.16: Tinh pH eila cac dung dich: a) CH3COOH 0,05M, Ka = 1,8.10'; b) acid orthohydroxybenzoic (HOC6H4COOH) 0,01M, Ka = 1,06.10-3 va c) HCN 1,0.10-4M, Ka = 6,2.10" Gidi
0,05 \>> 400, vay gia thik dung, nen pH = -1g(9,49.10-4) = 3,02 0,01 sai Phai dp dung (9-60) bang each giai phUong trinh bac hai, tim thgy: [H301 = 2,77.10-3M Vi gia tri >> 4,47.10-7M nen c6 the sii dung va tim duoc: pH = -1g(2,77.10') = 2,56
Tuy nhien, de dp dung dude (9-59) theo each tinh gam citing vdi gia thik - 5%, ta xet mA.0 so cua no Neu 3012 / Ca 5% thi (9-59) tra thanh: [H301 Kn [H30+ 12 - Kri Ka = , do [H301 = VKaCa + Kn (9-62) Ca Ka = (9-60) tra gia thiet 5%:
(162) Chit sau dp dung (9-62) de tim [H301, can kie'm tra lai xem gia thie't 5% c6 dung khong Clang c6 th6 ra tieu chi xet truoc ap dung (4,47.10-7 )2 - 10-14 Ca = 8,49.10-6M Thtic cong thClc (9-62) diloc dp 4,47.10-7.0,05 dung cho tat ca cac trtiang hop, trif dung dich c6 Ca qua nhO TrO lai vi du dang xet, vi Ca = 1,0.10-4M > 8,49.10-6M.nen dp dung difoc (9-62), tim thay: [H301 = 6,2.10-10.10-4 +10-14 = 2,68.19-7M va pH = -1g(2,68.10-7) = 6,57 - Tinh pH clia dung dich mot base yeti coon Dung dich chi chfia mot base ygu nen (9-58) Ca = 0; thay Kn , [H30+] = Kn , thay Ka = va sap xep lai thi (9-58) tra thanh: [OH-] Kb [OH- ]2 -Kn Kb = (9-63) Cb [OH ]2 - Kn [OW] Ph-tiong trinh (9-63) cho phep tinh [01-11, tit tinh [H301 va pH hoan toan chinh xac cho bat kST dung dich nao chlia mot base yeu nuoc Bang lap luan hoan toan Wong tai nhit deci voi acid ye-u ci tren to tim &foe cong thfic tinh ga'n dung [OW] cho tiing.trtiiing hop gioi han sai s6 5% Ngu [OH-] > 4,47.10'M thi bO qua [OH-] nude dien ly ra, (9-63) tra thanh: [OH ]2 Cb - [OW] Cb Ngu ([0H-]/Cb) < 5% hay Kb > 400 thi sii dung cong thfic: [OH b -]2 Kb - [OW] = A/Kb Cb C Noi chung, ngu Cb 8,49.10-6M dgu có thg dp dung: (9-65) [OW] = A/KbCb + Kn (9-66) (163) + Vi du 9.17: Tinh pH caa dung dich cocain base 0,0025M Bi6t cocain base (dung gay to niem mac mat, mieng, nieu dao) có cong thfic C17H2INO4 va Kb = 2,6.10 Gidi Ap dung cong thitc (9-66) vi Cb = 0,0025M > 8,49.10-6M, tim &toe: [OH] = V2,6.10-6.0,0025 + 10-14 = 8,06.10-5M pH = 14 + lg(8,06.10-5) = 9,91 Tinh pH cz1a dung dich cha'a mot cap acid - base lien hdp: Nhu vay dung dich se g6m met acid yezu va mu6i cua no, chang han CH3COOH/NaCH3C00; hoac met base y6u va mu6i cua no, chang han NH4C1/NH3 clung duoc them vao nuOc Vi Ca, Cb chwc them vao nen nhin chung 16n hdn nhieu [H30-1 va [OW] \Tay phuong trinh (9-58) tra thanh: Cb (9-67) + VI du 9.18: Tinh pH cila dung dich: a) CH3COOH 0,12M va NaCH3COO 0,16M ; b) NH3 0,3M va NH4C1 0,2M Gidi
(1,8.10-5 ).0,12 [H30-1 = = 1,35.10-5M 0,16 va pH = -1g(1,35.10-5) = 4,87 Kn 10-14 Kb(NH3) 1,76.10-5 10-14 pH = -1g( x ) = 9,42 1,76.10-5 0,3 C Dung dich acid, base da chic - Tinh pH cUa dung dich mot acid da chac: Hau h6t cac acid y6u da chic FInA có nac phan ly truck lOn hdn rat nhieu n'ac phan ly k6 ti6p (Kai/Kai_l 104) Do do, Kal/Ka., 103 + 104 ngtfai to xem [H30-1 chu y6u duoc tao tit buck phan ly thit nh'at va viec tinh pH cila dung dich acid da chfic Wong tai nhu d6i voi dung dich acid y6u don chfic + Vi du 9.19: Tinh pH ciia dung dich H3PO4 5,0M KaCa [H301 =
(164) Gicii Vi Kal/Ka2 = (7,5.10-3)46,2.10-8) = 1,2.105 nen dp dung theo cong tlpic (9-61) de tim: pH = -1g V7,5.10-3.5 = 0,71 - Tinh pH c eta dung dich mot base da chac: Giong nha deci vdi acid y6u da chile d tren, Kbl/Kb2 cz-=, 103 104 thi tinh pH tticing ta nha d6i vdi dung dich base ye.0 don chic + Vi du 9.20: Tinh pH cila dung dich Na3PO4 0,55M Gidi Vi Kbi(P043-)/Kb2(H2P042-) = (2,8.102)/1,6.10') = 1,75.105 nen dp dung (9-65) va tinh: pH = 14 + lgV2,8.10-2.0,55 = 13,09 Chu y": trtiong hop cac hang s6 dign ly Kal, Ka2 hoac Kbi, Kb2 khac nhau khong nhigu thi cach tinh pH can theo phtiong phap phlic tap hon D Tinh pH eau dung dich muol Cac muoi daoc xem lah6n hop cUa acid va base Trong ntidc cluing din ly hoan toan cac ion Cac ion có thg thing tac vdi cac ion H30+ va OW milk dign ly ra, vi thg dung dich mu6i có nhung gia tri pH khac ma to có thg dii doom va tinh duoc - Mu6i cila acid manh va base manh tao dung dich trung tinh (pH 7) vi cac ion khong phan ling vdi nadc Chang han: H2O NaCI (r) Na+ + Cl- a= 100% Na+ la acid vo cling ygu vi la cation cila mot base manh (NaOH) nen khong phan ang vdi naoc Cr la mot base vo cang y-gu vi la anion clia mot acid manh (HC1) cling khong phan iing vdi naoc Trong dung dich chi có nuoc din ly nen moi truing la trung tinh ThuOc loai gi3m cac mu6i tao bai ion kim loai IA, IIA (trii Be') vdi anion cUa acid manh NO3-, Cr, Br-, I-, CI04, HSO4- - Mu6i cila acid manh va base ygu tao dung dich có tinh acid (pH < 7) vi cation phan ling nha mot acid ygu, anion thi khong + Vi du 9.21: Tinh pH cila dung dich AlC13 0,010M, bigt Ka 3+ Al(H20)6 (165) Gidi Cation A13+ dung dich la mot acid ygu phan iing voi Al(1-170)63+ + H2O Al(OH)(H20)52+ + pH dm dung dich di16c tinh Dint d6i v6i mot acid 376u Ap dung cong thfic (9-61), tim dtioc: [H301 = V1,2.10-5.0,01 = 3,46.10'M thoa man gia thigt 5% nen pH = -1g(3,46.10-4) = 3,46 Vi du muoi thu6c loai nInt: Al2(SO4)3, Cu(NO3)2, (CH3NH3)2SO4, (CF13)2NH2Cl• • • - Mu6i cila acid ygu va base manh tao dung dich c6 tinh base (pH > 7) vi anion phan ling mot base ygu, cation thi khong + Vi du 9.22: Tinh pH ciia dung dich NaCH3COO 0,13M Gidi NaCH3C00 (r) H2O CC = 100% Na+ + CH3C00- Anion CH3C00- dung dich la mot base y6u phan ling vdi nti6c: CH3COO- + H2O CH3COOH + OH- Ap dung (9-65): • Kn 11 10 14 [OH] = ' Cb = 0,13 = 8,50.10-6M thoa man \ Ka(CH3COOH) 1,8.10- gia thigt 5% nen pH = 14 + lg(8,50.10-6) = 8,93 VI du mu6i thu6c loai flint KCN, Na2CO3, K3PO4, Ca(CN)2, K2S - Mu6i ciia acid ygu va base ygu tao dung dich c6 moi trii6n.g acid, base hay trung tinh phu thu6c vao d6 manh acid ho4c base tic:Mg doi cua cac ion + VI du 9.23: Tinh pH cila dung dich NH4CN 0,100M Gidi NH4CN H2O ■ NH4+ + CN- a = 100% (166) (1) NH4-F + H2O NH3 + H30+ Kam =5, 7.10 10 (2) CN- + H2O HCN + OH- Kb(2)= 1,6.10-5 Ka(2)= 6,2.10-10 (3) H2O + H2O H30+ + OH- Kn = 1,0.1014 va phan itng trung hoe gala acid NH4+ va base CN-: (4) NH4+ + CN- HCN + NH3 K = ? hgt tim cac cong thfic ly thuye't chung cho loai mu6i Tit can bang (4), cho: K [HCN] [NH3 ] = [NH3][H30+] x [HCN] Ka(1) (9-68) [NH4][CN-] [NW41 [CN ] [H301 Ka(2) Lap bang phan NH4 + CN- -1 - HCN + NH3 Ban dau Cm Cm 0 Bien d6i -x - -x x x d can bang Cm - x Cm - x x x (O day, C ang d() ban (tau cila mu6i, va di6u ki"0 de lap bang tren la KamC >> 10-14 va Ka(2)C >> 1044) Tit bang phan ling cho they [NH41 = [CN-] va [HCN] = [NH3], dila cac ang vao tich s6sau de thu dtioc: [NH3 ][H30+ ] x [CN-][H30+] \= = [11,012 [1\11-1-n [HCN] [H301 = NiKa(I)Ka(2) = pH = -1g.v/Ka(1) Ka(2) (9-69) Vay, pH ciia dung dich loai mu6i khong phu thuOc vao nOng dO muoi, chi phu thul)c vao gia tri caa hai hang s6 can bang Tra lai vi du cu the da cho, thu pH = -.1gV(5,7.10-1°) (6,2.10-1° ) = 9,23 5 DUNG INCH DEM CHAT CHI THI pH 5.1 Dung dich d'e'xn (167) Tinh chat cheng lai sti thay dei pH du de goi la tac dung &Om Chang han, rid& hoac dung dich NaC1 khong có tac dung dem, nen neu them 1mL dung dich HC1 0,1N vao 100mL nit& tinh khiet thi pH giam tit > Trai lai, h8n hop gem CH3COOH + NaCH3COO voi n6ng deng mol 0,01M c6 tac dung dem, nen cling them lmL dung dich HC1 0,1N vao 100mL hon help thi pH chi thay deci — 0,09 don vi to goi h8n hop vita neu la met dung dich dem Muen gift ditoc pH hang dinh, he dem (dung dich Om) can phai Chita met c6u tit c6 tinh acid de trung hoa OW them vao he va met cgu tit co tinh base de trung hoa H30+ them vao he Cac cgu tit khong the la acid va base bat kST, bill vi chung phai cling ton tai dung dich ma khong trung hoa ran RO rang, chi c6 the la c'au tit cua cling cap acid - base lien hop theo thuye't Bronsted - Lowry, vi du nInt cap CH3COOH/CH3COO— (h8n hop acid yeu va muoi cila no) da neu tren Cdn khai quat rang, mot he dem la mot dung dich caa cap acid - base lien ho'p ma tot nheit let n "dng de) cilia clang acid va caa clang base xdp xi Co the dem: h8n hop CH3COOH + NaCH3COO dung dich thiet lap can bang: CH3COOH + H2O CH3C00 + H30+ (9-70) [1-1/ 0+ 1[CH3C001 Ka = = 1,8 x 10-5 (9-71a) [CH 3C001-11 [CH1COOH] Rut ra: [H30+] = - [CH COO (9-71b) Muei NaCH3COO dien ly hoan toan: NaCH3COO —> Na+ + CH3C00- (9-72) nen [CH3C00 ]tu mu6i = [Muei] Vay: [CH3C00-]dung dich [CH3C00 ]tit muoi [CH3C00-]ti acid (9-73) Khi c6 mat gee cH3C00- tit muei voi lttong len thi can bang (9-70) bi d6y lui manh sang trai, CH3COOH lien ly da yeu lai cang yeu hdn, do c6 the bO qua [CH3C00-]tir acid, nen: [CH3C00-] dung dich = [CH3C 00 ]tii muOi = [MU6i]toan phdn ban ddu (168) Thay cac nemg tren vao pinking trinh (9-71b), ta có: [Acid] [H301 = K (9-74) a [Mu6i] [day chinh la phuong trinh (9-67) da bigt] Tit (9-74) tinh pH cila he dem CH3COOH/CH3C00-: pH = pKa + lg [Muoi] (9-75) [Acid] He dem dang xet gifi dude pH hang dinh, + Khi them met Wong acid manh (tfic la them H30+) vao he thi base cila he (la CH3C00-) se trung hoa va chuyen acid manh them vao acid ye-u cira chinh he qua phan H30+ (them vao) + CH3C00- > CH3COOH + H2O NhO do, pH cila he hdu nhti khon.g thay doi + Khi them met lacing base manh (tfic la tang them OH-) vao he thi acid cila he (la CH3COOH) se trung hoa qua phan CH3COOH + OH- (them vao) —> CH3C00- + H2O Nilo do, pH dia he gAn nInt &foe hang dinh + Vi pKa la hang s6, do pH cila dung dish dem chi phu thuec ty s6 [Mutii]/[Acid] Khi pha Mang, tY' s6 khong d6i (n4c du neMg muoi va acid deu giam), pH vi the ducic hang dinh — Phu'o'ng trinh dem: de khai quat cho he dem Om 'mit acid yeu (HA) ya mu6i cua no (A-, la dang base lien hop), ta co cac plitiong trinh chung: HA + H2O H30 + A- Ka — [H304 ][Al [HA] [H30+] = K [HA] [Acid] a [A: a [Base] pH = pKa + lg [HA] Wit chung cho moi cap acid base: pH = pKa + lg [Base] ] [Acid] (9-76) (9-77) (169) Phtiong trinh sau cfing goi la phtiong trinh Henderson + Vi du 9.24: Tinh pH dia dung dich dem:
Gidi
0,50 pH = 4,74 + lg - 4,74 0,50
ma n6ng acid (CH3COOH) cila he giam (0,50 - 0,02)M va ang base (CH3C00-, dang mu6i) cila he tang them (0,50 + 0,02)M V4y: 0,50 + 0,02 pH = 4,74 + lg = 4,77 0,50 - 0,02
ma no'ng base (CH3C00-) cua he giam (0,50 - 0,02)M va ang de acid (CH3COOH) cua he tang them (0,50 + 0,02)M V4y: 0,50 - 0,02 pH = 4,74 + lg = 4,71 0,50 + 0,02 Nh4n xet: du them base manh (NaOH) hay acid manh (HC1) vao he dem cu the nhu tren thi pH cila no clang chi thay dei ± 0,03 don vi pH, ttiong itng \Ted sit thay dei - 0,6% pH cila toan he Ghi chi": phuong trinh Henderson (9-78) duoc Alp dung chung cho dung dich dem chfia Op acid - base lien hop bat kST nao Tuy nhien, ngtfoi to cang phan biet trueng hop he dem duoc tao • C4p acid - base lien hop dang HA/A- [phtiong trinh (9-31)] la dung dich dem gem acid yeu va muoi c eta no, goi tat let he dem acid, Chang han (170) • Cap acid - base lien hop dang BH±/B [phuong trinh (9-32)] la dung dich dem gdm base ye-u va !nu& cita no, goi tat la he dem base Chang han NH4+(C1-5/NH3 ; ephedrin2+(S042-)/ephedrin base — Yeu to anh huOng den pH dia he dem: + IAlc ion ciia dung dich Khi them mu6i trung tinh bat kST nao vao he dem, lUc ion I ciia dung dich tang Nguroc lai, pha loang, lt,ic ion I ciia dung dich dOm giam Sti bie-n d6i laic ion &an den thay d6i he so hoat f ciia phan tao nen he dem, vi the pH ciia dung dich dem bi anh huOng + Nhiet Theo quy luat chung, trang thai can bang he dem thing thay d6i theo nhiet Tuy nhien, anh huOng nhO, ne-u nhiet de bi.en doi khoa.ng hep + Vi du 9.25: Mot dung dich dem chfia HCOOH 0,05M va NaHCOO 0,10M Dung dich cif) laic ion I = 0,10 Biet pKa cila acid formic bang 3,74, U./1h pH dm dung dich khi:
Gidi
0,05
X fBase [HCOCY x fHcoo_ pH = pKa + lg [Base] = pKa + lg [Acid] x fAcid [HCOOH] x fHCOOH Vi HCOOH la acid ye-u, n6ng di) nhe nen fricomi e-z% 1, vay: - pH = pKa + lg [HC00 ] [HCOOH] lg HC00- 0 10 0,51 V0,10 \= 3,74 + lg = 3,92 0,05 1,0 + V0,10 • Dung luting dem (/3): Kha nang ch6ng lai su thay deli pH cUa cac dung (171) la mot dai lilting de danh gia hieu luc dem, dUdc dinh nghia la so gia lu'o'ng base manh hay acid manh them vao de' pH thay dei dan vi Bigu thitc xac dinh 13 trung binh là: AB AA (9-79) ApH ApH ei day, AB, AA la so mol OW hay 111- cila base manh B hay acid manh A tao nen mat si thay dai ve pH ApH Chia y:• them AA thi ApH < nen phai dat dau - de 13 luon dtidng NInt \Tay, dung Wong dem f3 cim mot dung dich cang lon thi hieu hic dem (hay kha nang thong lai su thay dai pH) cang lon va nguoc lai 13 c6 gia tri bang them mol cUa base manh (hoac acid manh) vao lit dung dich dem gay si thay dal ddn vi pH + Pinking trinh Henderson (9-78) cho thay, pH cila dung dich dem chi phu thuac tY' so [Base]/[Acid] Dung Wong dem se lOn [Base] [Acid] Nglioc lai, nang do khac nhieu thi dung Wong dem cang nh6, hieu ldc dem ygu dan De minh hoa, to tra lai vi du 9.33: ts'T so [Base]/[Acid] = [CH3C00-]/[CH3COOH] = 0,50/0,50 = da cho ket qua pH chi thay d6i 0,03 ddn vi (= ApH) them 0,02 mol NaOH (= AB) vao lit dung dich dem, dung lucing dem tinh theo ding thitc (9-79) cho pi = '0,02/0,03 0,67 Gia sit bay gia thay doi ty so phan cUa dung dich dem khac 1, chang han [CH3C001/ [CH3COOH] = 0,40/0,60, dung dich hie c6: 0,40 pH = 4,74 + lg = 4,56 0,60 Neu van them 0,02 mol NaOH vao lit dung dich dem thi: 0,40 + 0,02 pH = 4,74 + lg = 4,60 0,60 - 0,02 V4y pH da thay diS'i 0,04 ddn vi \TA R2 = 0,02/0,04 = 0,50 nhO lion (31 da xet tren • Tom lai, 6 nang d6 nhat dinh, mat dung dich dem c6 pH = pKa (nghia la khi [Base] = [Acid]) thi dung lacing dem 13 cUa no la lon nhat Dieu kien "a nang d6 nhat dinh" duoc hieu la tang cua nang dO [Acid] + [Base] = Ca + Cb = C • Dung Wong dem tinh theo phuong trinh (9-79) chi la gan dung D6 dung litOng dem trung binh them base hay acid Neil vigt piniong trinh &Ai dang dao ham: (172) \= -2,303 (9-80) – d lg[H30+ ] d 1n[H30+ ] lai theo cac quan he: [H301 = Ka C a va C = Ca + Cb = const nen Cb dCb = -dCa, to có the rut phacing trinh tinh dung luring dem chinh xac \= 2,303 C Ka[H10+] (9-81) R dCb dpH dCb dCb (Ka +[H10± ])2 Nhu da biet, dung Wong dem clic dai xay pH = pKa hay [H30+] = Ka, cfing titc la Ca = Cb = 0,5C, piniong trinh (9-81) Ric tra thanh: [H1012 5Cx 0,5C _ La = 2,303 C x • – 2,303 0,576 C (9-82) (2 [H 30+ ])2 C Ta thay, ca R va13ma,, deu lon ang tong cac phan (C) lon, va ngticic lai Bdi vi C bieu thi cho tie'm nang cim met dung dich dem ch6ng lai ski thay d6i pH (them acid manh, base manh hay pha loang) • Wing dem la viing pH mad met he dem có kha nang digu hoa (gift pH hang dinh) tot nhat Ty so ang de dem [Base]/[Acid] cang khac 1, kha nang dem hay hieu hic dem cang yeu (tiic la dung hiring dem cang Thuc to cho biet, hieu luc dem tot nhat la cac niing ty s6 chenh Lech khong qua 10 ldn, nghia 0,1 < [Base]/[Acid] < 10, \Ta theo phucin.g trinh Henderson (9-78) thi: pH = pKa + lg10 = pKa + va pH = pKa + lg-1 = pica – 10 Vay, cac dung dich dem có vung dem sit dung &toe la pH = pKa ± Chang han, acid formic có pKa = 3,74 thi dung dich dem g6m HCOOH + NaHCOO chi duoc pha the viing pH tit 2,74 den 4,74 Ket Juan quan trong:
+ Gia tri ty le [Base]/[Acid], va cang lon ty le gAn tOi dcin vi + Do lOn cua moi n6ng cac phan dem, va cang lon ca [Base] (173)
+ VI du 9.26: Tinh dung lacing dem cua dung dich g6m CH3COOH + NaCH3COO c6 n6ng d6 d6ng mol 0,50M - Gidi Dung phuong trinh (9-81) voi Ca = Cb = 0,50M duoc: 0,50 0,50 13 = 2,303 x = 0,576 (0,50 + 0,50) Day cling la gia tri voi cac dung dich c6 C = Ca + Cb = 1M • Vi du 9.27: Hay die'u che mot dung dich dem pH = 5,00 va c6 dung Wong dem 13 = 0,20 Gidi
[Mu6i] [Acid]
(10-4,74 + 10-5,00 )2 C = 0,379 mol/L
tit 3) c6 C = [Mu6i] + [Acid] = 0,379 do d6 [Acid] = 0,134 mol/L [Mu6i] = 1,82 x [Acid] = 0,244 mol/L Chu 51: cach giai tren day c6 the coi la cac buck tien hanh chung de pha che cac dung dich dem khac theo yeu cau dat track - Vai tr.() va ling dung Oa dung dich dem: + Mau nga6i c6 pH on dinh khoang 7,4 Khi pH nh6 hdn 6,9 hoac 16n hdn 7,8 bieu hien cim nhang benh nang, tinh mang bi de doa 5 = 4,74 + lg nen [Mu6i]/[Acid] = 1,82/1 (174) \= 2,303 x 0,02625 x (4,5 x 10-7 + 4,0 x 10 )2 H,CO, / NaHCO, (4,5 x 10-7 ) (4,0 x 10-8 ) Chang han, pH dia mau benh nhan tieu &fang bi lion me thap den 6,8 pH dia mau diloc tri hang dinh, mac du ngtthi c6 the sii dung nhieu ngu6n dinh &tang pinac tap qua an uSng hang ngay, bai vi mau c6 nhting chat goi la chat dem huyet toting va hang eau tao nhung he dem, vi du H2CO3/(NOHCO3; (Na+)H2PO4-/ (NO2HP042- va cac protein huyet tticing; hemoglobin/oxyhemoglobin te bao hang cdu + Vi du 9.28:
phan khac huyet Wong - 0,004, tinh dung It dem cila cac te bao hang cdu Gidi
ngtfdi binh thliang c6 pH = 7,4 va luc ion I 0,20, thi: 7,4 = 6,3 + lg [NaHCO 0,51 V0,20 [H CO3 [ 1,0 + V0,20 Tim thay: [NaHCO1 [NaHCO ] lg 1,3 va 20/1 [H CO3 ] [H CO3 ] Rat dung thuc te, vi to xac dinh dttoc natri bicarbonat (NaHCO3) trong mau la khoang 0,025M va acid carbonic (H2CO3) mau (do CO2 hoa tan) la khoang 0,00125M
C = [NaHCO3] + [H2CO3] = 0,025 + 0,00125 = 0,02625M va Ka(H2co,) = 4,5 x 10', pH sinh 1ST 7,4 -Wong iing [H301 = 4,0 x 10-8M thi plittong trinh (9-81) cho ket qua: (175)
Ptoan phAn cila mau = Phuye't tUdng cAu \= (i3 H,CO3 /NaHCO3 131thac) Ph6ng cdu 0,039 = 0,005 + 0,004 + (hong cau ket quar3b6ng ,,,u = 0,03 Vay, he dem hemoglobin/oxyhemoglobin cila hang cau gift vai tra guy& clink tinh dem dm mau toan phan Cac dung dich dem ghi Duoc dien duoc dung thiic han.h Duoc khoa, dac biet tong thiac pha the thuac nhO mat pH dia nueic mat khoang 7,4, thay doi khoang - hoac hdi cao hcin Dich nUoc mat c6 dung Wong dem lon, cho phep pha loang 1: 15 voi nude cat trung tinh ma diva c6 thay do2i yd pH He dem gam acid boric, natri borat va NaC1 du de tao han hop dang truong, duoc sit dung cho cac dung dich thuac tra mat có pH - Noi chung, cac thuac dung ngoai clang tieu hoa (nInt de tiem vao mau, tra mat, nhO tai, nhO mai hoac dung cho cac be mat trot) c6 pH khac nhau, nhung thuong khong can dem de có the nhanh thong dua chung ve khoang pH sinh 1Y Truang hop pH dia thuac va dich co the khac nhieu ma gay kith iing tai cho thi có the dem nhe voi dung Wong dem thap Can biet rang, dang khong dien ly cua mot thudc acid yeit hay base yeic thu'eing có hoat tinh dieu tri cao ho'n dang mudi dien ly Bdi vi, dang khong dien ly tan lipid va c6 the tham than vao cac mang cUa cd the nhanh hon, dO dang ion dia thuac khong tan lipid, kilo tham thau qua cac mang de den dich can tac dung Chang han, cac alcaloid base ygu lam thuac tra mat c6 sit tang dap Ung dieu tri pH ciia dung dich tang, vi theo n6ng dia dang base khong dien ly tang len pH khoang 4, cac thuac a dang ion trai hdn, tham thau chain hoac khong dang ke Khi nu& mat dua thuac vg pH 7,4, thuac ton tai mite clang ke dang base to do, phu thuac yap hang s6 dign ly dia no + Vi du 9.29: Pilocarpin C11H16N202 (thuac co clang tit dung cho mat; dieu tri tang n.han ap, glocom grit mei) mat alcaloid, co pKb = 7,15 a (176) Gidi Khi tra thu6c, nu&c mat c6 can bang: CI1H16N202 pilocarpin Bang base + H2O CIII-116N202H+ + OH - pilocarrpin ion (dang acid, clang mu6i) Theo phoing trinh Henderson (9-78), to c6: pK + lg [Base] [Base] pH a = (14 — pKb) + lg [Acid] [MuOi] 7,4 = (14 7,15) + lg [Base] lg = 0,55 [Mu6i] [Base] [Mu6i] % mol base [Base] [Mu6i] + [Base] x 100 3,55 1 + 3,55 Trong thuc t6, a tang dO tan dia mot base alcaloid, ngtiili ta,pha the thu6c pH thap (\Tung acid), hodc dung dang mu6i de" tan (chang han, pilocarpin hydroclorid), vi dang base to ii pH cao thliong bi ket,tila tit dung dich Nlyti vdy, dung dich phai duoc dem pH thap de bao quan (ngan ngita thu6c bi ket tila thug tinh tao pH kiem, hodc ch6ng 10 s-ki tang acid CO2 tit khong hod tan) Thu6c &toe dem nhe ((3 nh6) d pH thap se dtfOc nuoc mat dieu hod ve pH cao va dang base tti duoc giai phong nhieu bon dap iing cho dieu - Dung dial dem duoc dung rOng rai nhieu link ciia hod hoc, vi du pinking phap mau; phan tich dinh tinh, dinh lacing; ddc biet la tien hanh cdc phan itng len men vi sinh vat, cling nhu tat ca cdc nghien dill ma can gilt pH khong d6i Co mot dem thuang duoc sii dung nghien oat' sinh hoc la Tris - (hydroxymethyl) aminomethan (HOCH2)3CNH2 goi tat la dem Tris hay Tham 5.2 Chk chi thi acid - base Co hai cach thong dung a do pH phOng thi nghiem bang may (pH-meter) va bang chat chi thi acid-base (con goi chat chi thi mau) Nguyen pH bang may se de cap ii chuong 10 (177) Chtft chi thi acid-base nhfing thudc the/ deic biet c6 mem sac thay ddoi tuj, theo Wong d6 ion H30' dung dich, Wen tuST theo pH mei truang NT& chung, có the xem chat chi thi mau la mot acid hi u co ygu ma clang acid (kY hieu HInd) có mau, goi tat mau acid, khac voi mau ciia clang base lien hop v6i no (Ind-), goi tat la mau base Nhu vay, su thay doi mau dm chi thi la std bign dOi eau frac phan tit gilla hai dang acid va base Trong dung dich, sit bign cle■i gii a hai dang the hien qua can bang dien ly phu thu§c vao pH: HInd + H2O acid base mau acid H30+ + Ind - (9-83) acid 2• base mau base Hang s6 can bang, cling goi hang s6 chi thi, theo (9-83) la: [H30+ ] [Ind] [HInd] [Ind- ] K Hind [HInd] [H30+ ] Hoac rat ra: KHInd Do do, (9-84) (9-85) (9-86) [Ind- ] [Base] pH = p11-HInd lg PKHInd ig [HInd] [Acid] Pinking trinh Wong &icing veil pinking trinh Henderson (9-78), vi can bang (9-83) chtoc vigt tthing dieing cho he dem Om acid ygu va mil& (base) cila no Theo pinking trinh (9-85), ro rang tST) s6 Oita hai dang base va acid cUa mot chat chi thi; not cach khac la tS7' s6 mau, ducic quygt dinh bOi [H30+] cua dung dich can tinh pH Su cam thu mau ciia mat nguai anh hang dgn viec sit dung cac chat chi thi Nguoi lam thuc nghiem se nhin thay mau ciia Ind- ngu ty s6 [Ind-]/HInd la 10/1 hoc loin hdn, va nhin thay mau cua HInd ngu tST so [Ind-]/HInd la 1/10 ho4c nhO hon Gifia giCsi han nay, cac mau ciia dang acid, base tr6n ran tao mau trung gian Mau ciia chi thi, vi vay la mot ham dm pH cUa dung dich Dua gia tri gi6i Kan 10 va 0,1 vao pliciong trinh (9-86), to tim thay: pH = PKiund ± (9-87) goi la khoang pH chuygn mau ciia chi thi, nam khoang don vi pH Trong yang pH chuyen mau, mau cila dang acid va base clang qua trinh chuyen doi nhau: mau cua dang dan dan sang mau cUa dang kia, hoac ngctoc lai (178) Bang 9.11 Mau, khoang pH chuyen mau va picho dm mot s6 chi thi acid - base hay gap Mau Khoang pH ,,, mau chuyen mau Chgt chi thi Base Xanh Xanh thymol (yUng acid) dO - yang 1,2 - 2,8 1,5 Tim methyl xanh - Um 1,5 - 3,2 2,1 Da cam methyl (heliantin) H6ng - yang 3,1 - 4,2 3,7 Luc bromocresol yang - xanh 3,8 - 5,4 4,7 DO methyl - yang 4,2 - 6,2 5,1 QuSt dO - xanh 5,0 - 8,0 Xanh bromothymol yang - xanh 6,0 - 7,6 7,0 DO cresol yang - dO 7,2 - 8,8 8,3 Xanh thymol (viang ki6m) yang - xanh 8,0 - 9,6 8,9 Phenolphtalein khOng mau - 8,2 - 10,0 9,4 yang alizarin yang - tim 10,0 - 12,0 11,0 Indigo carmin xanh - yang 11,6 - 14,0 Ghi mat nguai ta có the nhay cam voi mau nay, it nhay cam yeti mau kia, nen ta có the nhan biet dtioc khoang pH chuyen mau hep hon, khong nhgt thiet phai each don vi pH Khi do, gia tri pKHind khong nam chinh gifia khoang pH chuyen mau + VI du 9.30: (179) OH OH OH OH + H2O C—OH + H30+ O 0- C O Tha Bang acid dang base khOng mau mau + 2H30+ • De xac dinh gan dung pH cim cac dung dich ng di ta ket hop met s6 chi thi mau vdi de tao cai goi la chi thi mew van ming Chang han h6n hop cila chi thi mau: methyl da cam, methyl a bromothymol xanh, thymol xanh va phenolphtalein d1dc tam len giay la met nhang giay chi thi van nang thuang dung NO bao phi met yang pH tit den 11 Khi mu'O'n xac dinh pH cita met dung dich, ngdi ta nhimg giay vao dung dich this r6i so sanh mau xuat hien tren giay vdi met thang mau mau (TA.' ghi chit gia tri pH cho moi mau sac) Ghi chez: b6i vi ban than cac chat chi thi cac acid (hay base), su them chung vao cac dung dich khong dem de xac dinh pH có the lam thay d6i pH cua chin.h dung dich this Ngoai ra, cac 376u to nhiet do, dung mei, khac (anh Intang den sit dien ly cUa chat chi thi), su có mat cita cac ion khac dung dich (anh huang den laic ion chung va he s6 host cac chat) cling lam mau sac clia chi thi thay d6i Vi vay, sit dung chat chi thi de tim pH can phai den cac dien kien Sai s6 tot nhat dat &toe phep bang chi thi mau vao khoang ± 0,1 don vi pH 6 CAN BANG TRONG DUNG DICH CflA CHAT DIEN LY IT TAN TICH SO TAN Khi hoa tan met chat dien ly it tan vao nude se tao met dung dich bao hoa, ton tai can bang di the gifia luOng chat ran du va cac ion dm no dung dich: MmXn (r) m Mn+ (aq) + n (aq) (9-88) (ran) (dung dich) (180) K [M rn X n (r) NOng pha ran la hang s6, nen: [m.+] m [Xm-] = K [M,„Xn] (r) = (9-89) Ky hieu sau ding goi la tich s6 tan ciia M„,Xn Mut vay, tich so n6ng cac ion ciia chat dien ly it tan dung dich bao boa, moi n6ng &toe luy thiia tticing itng voi he s6 pinking trinh dien ly, la met hang s6 nhiet de nhat dinh goi la tich s6 tan, kS7 hieu T Theo (9-88), neu Mi„Xn có de tan la S (mol/L) thi se tao mS (mol/L) ion M"-F va nS (mol/L) ion 'X''' Thay vao (9-89), to có: TNAmxu = [mS]m [nS]" = mm Sm+n (9-90) va S = m+n (mol/L) (9-91) n n Chu j,: cac s6 tay hod hoc thileng ghi tan la g/100g dung mei (H20) Khi lam cac phep tinh lien quan den T, can d6i don vi mol/L vdi stt gn dung xem 100g H2O 100mIL dung dich vi de tan cila chat rat nhO Nh i vay, biet duoc tan S thi tinh &toe T, ngttoc lai biet T thi tinh dtioc tan S cua met chat + VI du 9.31: Tinh:
Gidi
PbSO4 (r) Pb 2+ (aq) + S042- (aq) T PbSO4 = [Pb 2+ [s042-] Xem 100g nitric 100mL dung dich, de tan S (mol/L) cua PbSO4 S = 0,00425g PbSO4 x 1000 mL x mol PbSO4 100 mL L 303,3g PbSO4 1,40 x 10-4 M PbSO4 Sit dung pinking trinh (9-90) cho can bang da viet, d6i vei PbSO4 thi m (181) TPbSO4 [Pb"] [S042-] = S2 \= (1,40 x 10-4)2 = 1,96 x 10-8 b) D6i vdi PbF2 ta có: Pb 2+ (aq) + 2F - (aq) T PbF2 = [Pb 21 [F -] 0,64g PbF2 mol PbF2 \= 2,6 x 10-3 S _ x M PbF2 1 L 245,2g PbF2 Theo (9-90) dp dung cho can bang cila PbF2 da vie't thi m = va n = 2, nen: TPbF2 = [Pb2+] [F-12 = 11 x 22 x S1+2 \= 22 x (2,6 x 10-3)3 = 7,0 x 10-8 + VI du 9.32: tinh d6 tan cila Ca(OH)2 nttoc, biet Tca(oH), = 6,5 x 10' Gidi Can bang di the va bieu thi T cua Ca(OH)2: Ca(OH)2 (r) Ca 2+ + 20H T ca(OH)2 [Ca 21 [OH Ap dung phuong trinh (9-91) vdi m = 1, n = ta có: TCa(OH), S = 1+2 = 1'x22 6,5 x10-6 \= 1,2 x 10-2 M Cac gia tri cua T cho bie't dO tan tildng deCi cua cac hOp chat ion Khi cac chat dien ly cang s6 ion, nghia la m+n nhti nhau, va -tY so cation/anion hoac la m/n hay n/m thi T ezia chat tido cang ldn, dO tan cita no cang ldn, va ngu'o'c lai [suy tit phildng trinh (9-91)] Dieu duoc the hien qua bang 9.12 Bang 9.12 Quan he giCia T va c10 tan 25°C cela mot s6 hvp chit S6 ion Gong thUc Cation/anion T DO tan (M) 2 MgCO3 1/1 3,5 x 10-5 1,9 x 10-4 2 PbSO4 1/1 1,9 x 10-5 1,3 x 10-4 2 BaCrO4 1/1 2,1 x 10-1° 1,4 x 10-5 3 Ca(OH)2 1/2 6,5 x 10-5 1,2 x 10-2 3 BaF2 1/2 1,5 x 10-5 7,2 x 10-3 3 CaF2 1/2 3,2 x 10-11 2,0 x 10' 3 Ag2CrO4 2/1 2,6 x 10-12 8,7 x 10-5 (182) Met chat se ket tua tich so ang cac ion cUa no dung dich lon hcin tich se; tan Nvoc lai, tich s6 niing cto cac ion be hdn tich so tan thi chat chua ket tua, hoac ngu da c6 tua thi tila se tan Day chinh la di6u kien de ket tfia hay hoa tan met chat dien ly it tan + VI du 9.33: Cho bie't ket tUa co hinh hay khong cac truang hop sau:
Gicii
CaF2 (r) Ca 2+ (aq) + 2F - (aq) Tinh ang ctsfi mol/L cho cac ion: So mol Ca" dtta vao h6n hop = 0,30M Ca' x 0,100L = 0,030 mol Ca' 0,030 mol va [Ca'] = = 0,10 M Ca' • 0,100 L + 0,200 L SO' mol F- dila vao hem hop = 0,060M x 0,200L = 0,012 mol F- 0, va [F-] = 012 mol = 0,040M F- 0,100 L + 0,200 L Trongh6n hop, ta c6 tich s6 n6ng cac ion, liST hieu Q, la: Q = [Ca'] [F-]2 = 0,10 x 0,0402 = 1,6 x 10-4 > TCaF, = 3,2 x 1041 Vay, ket tua CaF2 phai dUdc tao b) Tim Q cua Ca3(PO4)2 theo can bang: Ca va sit dung cac dU lieu da cho, ta cluoc: Q = [Ca213 [P04312 = (1,0 x 10 9)3 (1,0 x 10-9)2 = 1,0 x 105 < Tca,(po,), = 1,2 x 10-29 Vay, chtia th6 hinh ket tua Ca3(PO4)3 o dong song dang xet 1,2 x 10 29 (183) - Nhfing ygu to anh hiteing den d6 tan cita chat dien ly it tan: * Anh huang clia ion d6ng loai: Ski có mat cila mot ion d6ng loai lam giam d6 tan dm chat dien ly Gia sii ta có dung dich bao hoa BaSO4: BaSO4 (r) Ba 2+ (aq) + 5042- (aq) T Baso4 = 1,1 x 10-1" O nhiet d6 xac dinh, T chi phu thu6c vao tich s6 ang d6 cac ion Neil n6ng d6 cUa mot ion nao tang len thi n6ng d6 cila ion phai giam xu6ng de giii cho T la mot hang s6 Chang han cho them vao dung dich tren mu6i Na2SO4 de tan, n6ng d6 ion d6ng loai S042- tang manh, mot phan S042- se ket hop voi ion Ba2+ tao tua BaSO4 nhieu han, can bang di the chuye'n dich sang trai theo thing nguyen ly Le Chatelier: BaSO4 (r) Ba 2+ (aq) + 5042- (aq, cOng them) vi the, d6 tan cila BaSO4 giam + Vi du 9.34: Be lam re net anh chup bang tia X doei voi cac viem loet &tang tieu hoa, trUoc chup, benh nhan dttoc u6ng BaSO4 (dang huye'n phu nuoc) lam thu6c can quang Vi ion Ba2+ tu rat d6c nen nguai ta da cho them Na2SO4 de tan vao thu6c can quang
mat Na2SO4 0,10M Giiii
51 = /1,1 x 10-1° = 1,0 x 10-5 M
[Ba2+] = S2 ; [50421 = S2 + 0,10 (184) Gia thiet S2 nhO có the bo qua, nen [S042-] 0,10 Vay: S2 x 0,10 = 1,1 x 10-19 S2 = 1,1 X 10-9 Gia thiet clang vi thoa man: 1,1x 10-9 x 100 << 5% 0,10
Si 1,0x10-5 M 9091 lan S2 1,1 x 10-9 M nghia la tan caa BaSO4, theo la [13a2+] tii dung dich Na2SO4 0,10M da giam di chiing ay lan, de an toan sit dung thueic vi the ding tang len ding so lan tilting iing * Anh hitang cila pH: Ion hydroni H30+ có anh IniOng lon den tan cila hop chat ion Neu hop chat chlia anion caa met acid yeu, s4 them H30+ (tit acid manh) lam tang tan dm no + Vi du 9.35: Them H30+ tit acid manh lam cac can bang di the sau chuyen manh sang phai, do lam tang de tan dia cac chat dien ly it tan: 1/ CaCO3 (r) Ca 2+ (aq) + C032 (aq) H30+ HCO3- H30+ [H2CO3] CO2 (k) + H2O Vi C032- la anion caa acid y6u H2CO3, nen có cac phan iing tren 2/ Cu(OH)2 (r) Cu 2+ (aq) + 20H - (aq) Vi OH- la anion cila acid rat yeti H2O, nen có phan OW + H30+ H2O 3/ FeS (r) Fe 2+ (aq) + HS - (aq) + OH - (aq) (185) VI SW, OH- la nhang anion dia acid rat y6u I-12S, H2O nen c6 phan HS- + H30+ -> H2S OH- + H30+ —> H2O • Nguuc lai, H30+ khong anh huang den cac can bang: AgCl(r) Ag+ (aq) + Cl (aq) PbBr2 (r) Pb 2+ (aq) + 2Br (aq) vi Cr, Br- la anion dia cac acid manh nen H30+ khong phan iing voi * Anh htaing cUa stt tao phfic: MOt ph6i tit lam tang tan cUa mot chat dien ly It tan n6u no tao cttidc ion phlic voi cation cila chat dien ly + Vi du 9.36: Be hien hinh tren phim den - tang, ngtfai ta loaf be) AgBr dtt tren phim sau chup bang dung dich natri thiosulfat (Na2S2O3) nha all tao ion phfic tan [Ag(S203)213 Tinh di) tan cUa AgBr a) Trong va b) Trong dung dich Na2S2O3 1,0M Cho bik: TAgBF = 5,0 x 1043 va hang s6 ben (con goi la hang so- tao phitc) Kb = 4,7 x 1013 Gidi
AgBr (r) Ag+ (aq) + Br - (aq) (1) TAgBr = [Ag+] [Br-] = 5,0 x 10-13 Bat dO tan dm AgBr ntiac la S1 Theo (9-91) voi m = n = 1, ta co: S1 = V5,0 x 10-13 = 7,1 x 10-7 M
Ag + (aq) + 2S2032- (aq) Ag(S203)23 (2) Kb = 4,7 x 1013 COng phtiong trinh (1) va (2) ta &toe pluiong trinh tong: (186) [Ag(S20023 ][Br- Kto'ng TAgBr X Kb • [S2 32 12 \= (5,0 x 10-1) (4,7 x 1013) = 24 Dat di) tan cila AgBr dung dich Na2S2O3 1,0M la S2 Theo (3) to thay d can bang thi: S2 = [AgBr]haa tan = [Ag(S203)23 [S2031 = (1,0 - S2) Thay cac n6ng dO vao KttIng, thu &Joe: S2 X S2 Kt eing = 24 (1,0 - 2S2 )2 1,0 - S2 S2 = 0,45 M Do Ag+ tao phfic vdi S2032 nen dO tan dia AgBr da tang tii 7,1 x 10-7 M (trong milk) len 0,45 M (trong dung dich Na2S203 1,0 M) * Anh htidng cua lite ion: Khi hie ion dia dung dich > 10-4 (do ket tua có dO tan ion, hoac sit có mat cila chat dien ly khac de, tan) thi mot n6ng dO ion bieu fir& tich s6 tan T phai dtioc nhan vdi he s6 boat dO f, Gila no Vi < 1, tich s6 n6ng dO cac ion bang T/fi ion len, dO tan S cua k6t tua vi the tang theo + Vi du 9.37: Tinh dO tan dia chi iodat (Pb(I03)2) a) Trong ntioc nguyen chat
Gicii Ph-doing trinh can bang di the cilia chi iodat &toe viol: Pb(I03)2 (r) Pb 2+ (aq) + 2103- (aq)
va [Br] S2 \= V24 = 4,9 S = TPb( 103 )2 1' X 22 \= 1,2 x10-13 (187) [gia thi6t dung, vi laic ion cUa dung dich tinh theo (9-19)] thu dU6c: I = —([Pb'] x 22 + [I03-] x 12) \= —(3,1 x 10-5 x 22 + x 3,1 x 10-5 x 12) = 9,3 x 10' b) Dung dich Mg(NO3)2 0,033M c6 luc ion: 1 I = —([Mg2+] x 22 + [NO3-] x 12) < 10-4 ) \= !(0,033 x 22 + x 0,033 x 12) = 0,099 0,1 > 10-4 nen can phai tinh f, dia cac ion theo phiicing trinh (9-27) iing voi I = 0,1: 0,51 x12 x V0,1 lgf1± = -0,12 fl± = 0,76 1 + V0,1 0,51 x 22 x V0,1 lg f2± = = -0,49 f2± = 0,32 1 + V0,1 (cling c6 the tra bang 9.3 de tim va cang thu dtt6c cac gia tri 0,76 va 0,32) Do bieu thfic T day phai vie't theo hoat (16' cac ion: Tpb(1o,), = a pb2c a210,_ = ([Pb2+] fpb2.) ([I03 ] _ )2 \= [Pb2+] [I0312 fpb2, f120,_ [Pb2+] [I0312 = f Tpb(102)2 f2 = 1,2 x 10-13 Pb 2+ io 0,32 x 0,762 \= '6,5 x 10-13 = TT' Xem T' la tich s6 tan ctla chi iodat dung dich Mg(NO3)2 0,033M, van dung (9-91) to c6: S' = 1+2 T' — 6,5x10 11 X 2 \= 5,5 x 10' M (188) (S' - S) x100% = (5,5 x 10-5M - 3,1 x10-5M) x100% = 77% S 3,1 x10-5 M 7 PHAN U'NG TRONG DUNG DICH DIEN LY Chat dien ly dung dich nttdc tach cac ion Cdc ion bi hydrat hod va thiet lap flirting trang thai can bang digu kien xac dinh Phan ling gitia cac ion dung dich dien ly cang tuan ,theo di6u kien nhiet dang, nghia la phan zing chi xdy AGp,< 0, can bang chuyen dich manh sang phdi tao cac scan phci'm let chat it tan (hod c it tan han), chat it dien ly (hodc it dien ly han), chat de bay hcii Phan a'ng giica cac chat dien ly dung dich ding xdy co tao phac chift hod' c co trao ddi electron (phdn ang oxy hod khd') Sau day la nhfing vi du minh hoa cho tang ke't visa neu, deing thai cang cho bi8t each trinh bay cac phan ling, cac quy tac ve tan rat can thiic hanh hod hoc deli voi dung dich cac chat dien ly Chu y cac quy Lidc chung: Phricing trinh phan ling chi vik mat miii ten ( >) theo chi6u xay phan ling Dg chi si chuye'n dich mat can bang thi them mui ten do, nhung dai hdn, len tren kST hieu (xem vi du 9.35) Chat dien ly manh (xem muc 1.1 tren) duct vie't dien ly hoan toan cac ion Chat it tan, chat it dien ly, chat de bay hdi di6u kien thuang vie't driOi Bang nguyen tit, phan Cac chat, cac ion dung dich nueic bi hydrat hod thi vik ky hieu (aq) kern theo 7.1 Phan ling tao chgt it tan (kgt tiia) Thi du: + Phan ling gitia bac nitrat va natri cromat ctricic bieu thi bai ph-acing trinh phan 2AgNO3 (aq) + Na2Cr04 (aq) —> Ag2CrO4 (r) + 2NaNO3 (aq) Phuong trinh ion day dir: 2Ag+ (aq) + 2NO3- (aq) + 2Na+ (aq) + Cr042- (aq) —> Ag2Cr04 (r) + 2Na+ (aq) + 2NO3- (aq) Pinking trinh ion nit gon: (189) pinidng trinh sau ding IA phan ling khai quat giita moi chat co the tach ion Ag+ voi moi chat có the tach ion Cr042- + Phan ling gilia bac sulfat va bari clorid: Pinking trinh phan Ag2SO4 (r) + BaC12 (aq) —> BaSO4 (r) + 2AgC1 (r) T = 1,5 x 10-5 1,1 x 104° 1,8 x 1010 chat it tan chat it tan lion Phiidng trinh ion: 2Ag+ (aq) 5042- (aq) + Ba2+ (aq) + 2C1- (aq) —> BaSO4 (r) + 2AgC1 (r) O day, pinking trinh ion day d6 ya phtiong trinh ion rut gon IA nhti - Do tan ciia cac chat di."0 ly dtioc danh gia Binh Wong qua tich so tan T va danh gia Binh tinh qua cac quy tac hoa tan (bang 9.13) Bang 9.13 NhCing quy ta5c v4 dO tan ceia cac hop chat ion nutic Cac chgt tan Ngoai 1'0 1 - Cac hpp chat cCia Na+, K+, NH4 " 2 - Cac clorid (C11 - 3 Cac bromid (Br) - Cac iodid (I-) - Cac sulfat (S042 ) 6 - Cac nitrat (NO3) va nitrit (NO2) - Cac clorat (CI03-), perclorat (CI04-), permanganat (Mn04 ) 8 - Cac acetat (CH3C00-) Hau nhu' khong c6 KhOng tan: AgCI, Hg2C12 Tan nutic nong: Pba2 KhOng tan: AgBr, Hg2Br2, PbBr2 Tan trung binh: HgBr2 KhOng tan: iodid cOa nhi6u kim loci Ong KhOng tan: BaSO4, PbSO4, HgSO4 Tan trung binh: CaSO4, SrSO4, Ag2SO4 Tan trung binh: AgNO2 Tan trung binh: KCIO4 Tan trung binh: AgCH3C00 Cac chat khong tan Ngoai 16 1 - Cac sulfid (S2-) 2 Cac oxyd (02-), hydroxyd (OH-) - - Cac carbonat (C032-), phosphat (P043-), arsenat (As043 ) Tan: sulfid cCia NH4+, Na+, K+, Mg2+, Ca2+ Tan: Li2O, LION, Na2O, NaOH, K20, KOH, BaO, Ba(OH)2 (190) 7.2 Phan Ting tao chk it di'n ly - chi ye-u IA phan iing trung hoa - Phan ling gift acid man.h va base manh: 2HC1 (aq) + Ba(OH)2 (aq) -> BaC12 (aq) + 2H20 (1) 211+ (aq) + 2C1- (aq) + (aq) + 20H- (aq) -f Ba2+ (aq) + 2C1- (aq) + 2H20 (1) 2H+ (aq) + 20H- (aq) -> 2H20 (1) hoc H+ (aq) + OH- (aq) -> H2O (1) Phudng trinh ion rut gon sau ding IA phan ling trung hoa tao midc dien ly rat ye-u - Phan ling gifia acid ye-u va base manh: CH3COOH (aq) + NaOH (aq) -> NaCH3C00 (aq) + H2O (1) CH3COOH (aq) + Na+ (aq) + OH- (aq) -> Na+ (aq) + CH3C00- (aq) + H2O (1) CH3COOH (aq) + OH- (aq) > CH3C00- (aq) + H2O (1) It dien ly it dien ly hdn nhi6u - Phan ling gift base yeu va acid manh: NH4OH (aq) + HNO3 (aq) -> NH4NO3 (aq) + 1120 (1) N1140H (aq) + II+ (aq) + NO3 (aq) -> NH4+ (aq) + NO3 (aq) + H2O (1) NH4OH (aq) + H+ (aq) -> NH4+ (aq) + H2O (1) it dien ly It di"e'n ly hdn nhi6u 7.3 Phan ling tao chk 116 bay hdi, chang han Na2S03 (aq) + 2HC1 (aq) 2NaC1 (aq) + SO2 (k) + H2O (1) 2Na+ (aq) + 5032- (aq) + 211+ (aq) + 2C1- (aq) -> 2Na+ (aq) + (aq) + SO2 (k) + H2O (1) (191) 7.4 Phan Ting tao phiic chgt ZnSO4 (aq) + 4NH3 (aq) [Zn(NH3)4] SO4 (aq) Zn(H20)42+ (aq) + S042- (aq) + 4NH3 (aq) —> [Zn(NH3)4]2+ (aq) + S042 (aq) + 4H20 (1) 7.5 Phan ling trao clEii electron (oxy hoa khit), chAng Phticing trinh phan 2KIVIn04 (aq) + 5CaC204 (aq) + 8H2SO4 (aq) —> kali permanganat calci oxalat 2MnSO4 (aq) + K2SO4 (aq) + 5CaSO4 (aq) + 100O2 (k) + 8H20 (1) Plitiong trinh ion d'ay 2K+ (aq) + 2Mn04 (aq) + 5Ca2+ (aq) + 5C2042- (aq) + 16H+ (aq) + 8S042- (aq) —> 2Mn2+ (aq) + 85042- (aq) + 2K+ (aq) + 5Ca2+ (aq) + 100O2 (k) + 8H20 (1) Plniong trinh ion rut gon: (192) MVC TIED 1 Tim du'dc men tru'ang (khocing pH) cho mot phcin zing oxy hod khet nha can being phu'Ung trinh theo phuzing phdp phdn 2 Trinh bay each xdc dinh cac the-dien cu'c chudn E; y nghia va van dung crux E 3 Thanh lap phudng trinh Nernst, va van dung phu'o'ng trinh de xdc dinh chie'u hu'dng va md'c di) dal phdn ring oxy hod 4 Gidi thich cd the hoat crOng dia pin ndng di) (di ang dung pH va gidi thich dien the mang to bao); ceia acquy; va aid srrt an mon him loci 5 Xcic dinh va tinh dude lacing sdn pham pin dien phitn Hieu du'o'c su' hinh theinh the dien hod va nang lu'o'ng lien ket te-bao Chticing 10 PHAN AG OXY HOA KFICi VA DONG HIEN 1 PHAN LANG OXY HOA KIIU' KHAI QUAT VE PIN HIEN HOA 1.1 Khai niem chung Phan Ung oxy hod khit la phan ttng có su chuy6'n dich electron gifia cac chat phan ling, do lam bie-n do7i s6 oxy hod cua cac nguyen to Chat oxy hod (phan tit, nguyen tit, ion), vie't tat: chdt Ox, la chgt nhan electron va giam s6 oxy hod, no la chg bi Chat khU' (phan tit, nguyen tit, ion), viet tat: chgt Kh, la chgt cho electron va tang s6 oxy hod, no la chdt bi oxy hod Theo suy ra: su' khei la su nhan electron Su' oxy hod la sit cho di electron Rdt can de khong nhdm ran cac thuat ch"dt oxy- hod., sit oxy hod, chat khit, su Vi du, dung dich nude xay phan (193) Ion Cu' nhan electron (tit Fe) la chat ox, s6 oxy hod dia no giarn tit +2 clgn 0, no bi khit va goi la sit khii ion Cu' (bai Fe) Sat cho electron nen la chat kh, so oxy hod cUa no tang tit den +2, no bi oxy hod va goi la su oxy hod sat (bai ion Cu') - Co the chia phan fing (10-1) nfia phan itng de) thay ro hdn ch'dt nhan electron va chat cho electron: Cu" + 2e Cu Fe Fe' + 2e Quy luat can bang cac nita phan itng gioeng nhu doi voi cac phan itng khac, nghia s6 nguyen tit cua moi nguyen to va dien tich cua moi vg pinking trinh phai nhu Mac du cac nita phan itng duoc tach rieng, nhting std mat electron va nhan electron xay d6ng thai So- electron mat bdi chdt bi oxy hoci luon tWing so- electron nkin du'oc bdi chdt bi khei Phan itng oxy hod khit (vigt tat: phan itng ox-kh) c6 the nhin nhan tucing tit nhtt phan ling acid-base theo khai niem cUa Bronsted-Lowry, bai vi ca loci phan itng de'u lien quan dgn slat van chuygn mot hay nhie'u lieu phan mang dien tit chat cho den chat nhan: electron phan itng ox-kh va proton phan ling trung hoa Khi mot acid cho di proton, no tra base lien hOp va c6 kha nang nhan proton Toeing tit, mot chat Kh cho electron, no tra mat chat Ox va co the nhan electron ma hinh thfic co the goi la chat Ox lien hop Tit d6, cac nits phan fing vigt d6c lap cling goi la cac cap oxy hoci khi' lien hop, chioc ky hieu va quy tiOc vigt: cap Ox/Kh Vi du: O phan Ung (10-1) c6 cap Ox/Kh la Cu2+/Cu va Fe/Fe Phan itng Ox-Kh la tong dm /lila phan itng, Wong fing vOi cap Ox/Kh vigt day Oxl + nle Khi Kh2 Ox2 + n2e Va vi so electron cad chdt Kh cho phai bang so- electron cila chat Ox nhan, nen phuong trinh tong quat cilia phan ling Ox-Kh c6 the vigt: n20x1 + n1Kh2 n2Kh1 + n10x2 (10-2) (194) 1.2 S6 oxy hoa (S.0) - S6 oxy hod (con goi IA mite oxy hod, trang thdi oxy hod) IA din tich hinh thfic cua nguyen to don chat, ion hay hop chat quy uric cac cap electron dung chungl8ch hoAn than ve nguyen to c6 dO am din lon hon Chit Srrang, S.0 cUa nguyen to c6 gid tri dai so khdc hod tri S.0 c6 the s6 am, s6 &tong hoac bang khong Trdi lai, hod tri tinh theo s6 electron tham gia lien ke't nen chi c6 gia tri during - S.0 dm mot nguyen to duoc xdc ctinh the() nhfing quy vac' sau: Quy tcic chung: 1/ Nguyen to don chat (Na, Cu, 02, N2, S); ,S.0 = 2/ Nguy8n to ion don nguy8n tit: S.0 = di.8ntich ion 3/ Tang dai s6 S.0 dia cac nguyen to phan tit = 0, ion nhi6u nguyen tit = din tich ion Quy tat cu the'cho cac nguyen tit hoac nh6m nguyen to Bang tuan hoan: 1/ Nhom IA: S.0 = +1 tat ca cac hop chat 2/ Nh6m IIA: S.0 = +2 tat ca cac hdp chat 3/ Hydro: S.0 = +1 cac hdp chat vdi phi kim S.0 = -1 cac hop chat V6i kim loaf va Bor 4/ Fluor: S.0 = -1 moi hdp chat 5/ Oxy: S.0 = -1 cac hop chat peroxyd S.0 = -2 tat ca cac hop chat khdc (tru vdi fluor) 6/ Nhom VIIA: S.0 = -1 cac hop chat vdi kim loaf, vol plii kim (trit vdi oxy) va vdi cac halogen khdc phia du6i nhom Lau 31: 1/ S.0 diking cao nhat cita cac nguy8n to cac nh6m chinhA bang s6 this to cua nhom (trit va F) 2/ S.0 dm thap nhat cua cac phi kim va mot s6 a kim bang s6 thi tit cita nhom frit Vi du: ktu huSm.h.;c6 S.0 during cao nhgt +6 (vi nguyen to S o nhom VI A) nhu hop chAl SF6 va c6 S.0 am thap nhat = - 8= -2 nhu FeS (195) nguyen to Bang tun hoan C6n n6u kh8ng biet r5 cgu tao phan tit thi S.0 xdc dinh &toe tit cac nguyen tae da neu co the la S.O gia Chang haa,,dat S.0 ciia lUu huynh la x, tim duoc S.0 cua no 52082- qua pinking trinh: (x.2) + (-2.8) = -2 x = +7 Day la s6 oxy hod gia, vi lttu huYnh o nhom VIA, S.0 cao nhat cua no chi la +6 plul hop voi cong thlic eau tao: hoac -o\ -0\ ,0- , s, s, „ O' 0 0\ - 0/ \ / 0- z% 0 00 Hon ncia, gap so oxy hod gia va le, nhti S Na2S406 cO S.0 = +2,5 Tuy nhien, S.0 that hay gia deu có gia tri nhU can bang phuong trinh cua phan itng Ox-Kh 1.3 Can bang phan itng oxy hoa khif Co nhieu phuong phap de can bang phan itng Ox-Kh, nhung thitang dtiOc sit dung la phuong phap s6 oxy hod, va quan hdn la phtiong phap nfia phan fing 1.3.1 Phu'o'ng phcip so oxy hod Duoc thuc hien theo cac bit& sau: 1/ Viet cac chat dal' (chat phan Ung) va cac sari pham Vi du: HC103 + P -> HC1 + H3PO4 (di nhien chat dAu da biet, nhung san pham gi thi phai dita vao cac phep phan tich hod hoc hoac can cit vao quy luat bien dOi cua cac nguyen to va hop chat) 2/ Xac dinh S.0 cua cac nguyen to trade va sau pilau ling O vi du tren, tim thay: HC15+03 + P° -> HC11- + H3P5+04 3/ Tim so electron ma phan tit chat khii cho va s6 electron ma phan tit chat oxy hoa nhan, tit lap phuong trinh trao &di electron de tim he s6 chinh cua chat khit va chat oxy hod Ti6p vi du tren, lap: 61P° - 5e -> P5+ *15+ + 6e —÷ C11- (196) 4/ Oat he s6 chinh phis hdp vao cac chdt khit va chgt oxy hod ban ddu, kiem tra s6 nguyen tit ciia nguyen to d ve pinking trinh de can bang chting nhung chua can chi] Y den s6 nguyen tii H va (nefu nguyen 16 khong truc tiep chgt khit hay chgt oxy hod) Tiep theo vi du tren, thu duoc: 5HC103 + P = 51,-1C1 + H3PO4 5/ Kiem tra s6 nguyen ti H ve de tim s6 phan tit int& tham gia hoac tao Vdi vi du dang xet, can phan tit H2O tham gia phan ling Vay: 5HC103 + 6P + 9H20 = 5HC1 + 6H3PO4 6/ Kiem tra lai s6 nguyen tit d v6 va tin rang thuc chgt phuong trinh da duoc can bang Vdi buoc tien hanh nhu tren, moi phan ling oxy hod khit viet diidi clang pinking trinh phan tii deu có the &toe can bang Tuy nhien, nhieutrliang hop khOng can thiic hien du cac buoc va da quen thi chi can nlidm tinh tren mot phtiong trinh phan ling 1.3.2 Phtto'ng phcip nita phdn zing - Pinking phap can bang quan va có nhieu loi ich, bai vi: + Noi chung, khong yeu cdu viec xac dinh S.0 ciia moi nguyen to + Tdch qud trinh Ox-Kh niia phan ling se phan dnh ban chdt thuc xay rad dien cue pin dien hoa (gioi thieu muc sau) + Lam chO viec can bang cac phan ling Ox-Kh de dang hdn chung xay moi truang acid hay base, dieu thuang gap cac pin - Cac bade tien hanh Noi chung, to bat ddu vdi "130 khung phan ling ion", chi viet dang Ox va dang Kh, chua can chit Sr H2O, H+ hay 0H 1/ Chia 13O khung phan iing rata phan ling (nita nao la Kh, rata nao la Ox se ro rang a cac buck tiep theo) 2/ Can bang cac nguyen tit va dien tich moi nita phan ling (electron cluoc them vao ben trdi cua niia phan ling Kh va vao ben phai cua nita phan ling Ox) 3/ Nhan moi niia phan ling vdi mot s6 nguyen, neu can thiet, d6 s6 electron nhan niia phan iing Kh bang s6 electron cho d.niia phan itng Ox 4/ COng cac nita phan ling da can bang de thu dtioc phan ling tong (chd ghi kern ca trang thai chdt) (197) - Can bang phan ling Ox-Kh moi trtiong acid: H20, 1-1+ va electron se duoc sii dung qua trinh can bang Vi du, c6 phan ring vdi 136 khung la: Cr2072-(aq) + 1-(aq) -> Cr3+(aq) + I2(r) 1/ Tach niia phan ling: Cr2072- Cr' I- > 12 2/ Can bang nguyen tii va dien tich moi niia phan ling Cluj y: sii dung H2O de can bang,s6 nguyen 0, dung H+ de can bang s6 nguyen tii H, va electron de can bang dien tich: Vdi nita phan iing Cr2072-/Cr' thi:
Cr2072 -> 2Cr' + 7H20 c) Can bang H phai them 14H+ vao ye trai, duoc: Cr2072- + 14H+ > 2Cr' + 7H20 d) Can bang dien tich doing phai them 6e vao v6 trai, dtioc: Cr2072- + 141-14- + 6e > 2Cr' + 7H20 Vay, niia phan iing da dti6c can bang, va day la nita phan iing Kh (qua trinh Kh, sti Kh) vi electron da dtioc nhan vao (ben trai) Ta hieu rang Cr2072 chat Ox, va Cr' bi khii - Vdi nita phan ling 1-/12, toeing ling vdi cac btfoc phan ling da xet tren, thi:
Vay, nUa phan ling 1-/I2 da &foe can 'bang, va day la nita phan ling Ox (qua trinh Ox, su Ox) vi mat electron, I la chat Kh va bi Ox 3/ Nhan moi niia phan ung vdi mot s6 nguyen can thiet de s6 e mat ski Ox bang so/ e nhan sti Kh: 1x1 Cr2072- + 14H+ + 6e -> 2Cr' + 7H20 (198) 4/ COng rata phaniing cra can bang, xoa di nhfing chgt xu'at hien a ca hai NT6 (a' day chi có 6e) de thu dude phan ang tang (chti y ghi trang thai chgt cua cac cgu tii): Cr2072- (aq) + 6I-(aq) + 14H+(aq) -> 2Cr3+ (aq) SI2 (r) - + 7H20(1) 5/ Kiem tra s6 nguyen tit va dien tich ye cita phan ling tang: tat ca deu dung Tit cling cho thgy, phan ling can dadc tien hanh moi traang acid Tit phan ang tang cila clang ph-acing trinh ion tren day to có the viet lai duoi dang phucing trinh phan tit cho cac chat cu the, neu can thi6t - Can bang phan ling Ox-Kh moi truong base: Tien hanh cac budc nlya moi tritong acid, chi có su thay dai a bade 4/: thay s6 H+ xugt hien phan ang tang bang s6 OH- vao ca ye va mot Ian nila don gian so phan tit H2O a ye cuaptatung trinh Vi du, natri permanganat NaMnO4 phan iing vdi natri oxalat Na2C2O4 moi traang NaOH tao chgt ran Mn02 va carbonat C032- Bo "khung phan ling ion" la: Mn04-(aq) + C2042-(aq) -> Mn02(r) + C032-(aq) 1/ Tach niia phan ling: Mn04 -> Mn02 va C2042 -> 0032- 2/ Can bang nguyen tit va dien tisch a moi n.ita phan ling theo trinh (nha vi du moi truang acid), thu &toe ket qua: Mn04- + 4H+ + 3e -> Mn02 + 2H20 (niia phan ling Kb) C2042- + 2H20 -> 2C032 + 4H+ + 2e (nita phan ling Ox) 3/ Nhan moi nita phan ang vdi mot s6 nguyen de so- electron nhan bang so- electron cho: nhan va 1Am Ludt vao niia phan iing teen, cludc: 2Mn04- + 8H+ + 6e -> 2MnO2 + 4H20 3C2042- + 6H20 -> 6C032- + 12H+ + 6e 4/ COng nita phan ang TA.' can bang, don gian cac cau tit gi6ng a 2 ye, thu duck phan ling tang: 2Mn04- + 3C2042- + 2H20 -> 2MnO2 + 6C032- + 4H+ Can bang cho thgy, phan ling can tien hanh moi truang kiem Vay, them 40H- vao y6 (14 trung hoa 4H+ va mot Lan naa don gian s6 phan tit H2O a ye: (199) Phan ling tang sau cling la: 2Mn04 (aq) 3C2042-(aq) + 40H- (aq) —> 2Mn02 (r) + 6C032- (aq) + 21120(1) 5/ Kiem tra nguyen tit va dien tich ye: Tat a deli diing Tra lai thvc to phan ling ban dau la dling cac muol natri moi truang NaOH thi piniong trinh phan tit se la: 2NaMnO4(aq)+ 3Na2C204(aq)+4Na0H(aq)—>2Mn02(r)+6Na2CO3(aq)+ 2H20(1) Tat nhien, ne-u H+ khong xuat hien can bang cac nits phan ling thi cling khong có buoc triet tieu no bang OH- moi trUang base, nghia la phan ling co the xay moi truang trung tinh 1.4 Khai gnat y6 pin dien hoa MOt phan ling Ox-Kh có the xay dung dich trOn ran chat Kh phan -tang Ox) va chat Ox phan ling Kh) O day, slt trao d6i electron la va cham trite tip gifia chat Ox va chat Kh Nang hiOng hod hoc bign nhiet Neu bang each nao tach rien.g hoan toan (ve mat vat VT) niia phan fing va buOc sit trao d6i electron phai qua mot day dan, ta thu dttoc dung dien o day, nang Wong hoa hoc bign dien nang Mot thigt bi bat kST cho ta thu &toe &mg dien nho mot phan -tang Ox-Kh, hoac nha dong dien ma mot phan iing Ox-Kh có the xay ra, dtioc goi la pin dien hod Dua tren nhiet d'Ong hod hoc, pin dien hod duoc chia lam loai: 1/ Pin Galvanic (hoac Voltaic) sit dung nang Wong cila phan iing ti phat (AG<O) de phat dien nang He phan ling tao ding cho moi truang Tat ca cac acquy deu chlia pin Galvanic (200) Phatra 4n rang Naa phan ang Ox A- - A + Pin &Yel phan Pin Galvanic Anod (Sir Ox) Nang Itrong Chat din phan Catod (Sir Kh) Naa phan ang x X4X++e- Nira phan ang Kh Y+ Y Phan ang tong pin X+Y± X+ +Y; AG<0 Nth phan ang Kh e- + B± B Phan ang t6ng pin A- + B± A + B; AG > Hinh 10.1 NhCing dac drain dal Wong coa pin Galvanic va pin than phan (cho dien tich tu'ong d6i coa dien cut a pin la ngu'dc nhau, nhu'ng chiau di chuyen cOa electron tit anod tai catod van khOng thay d6i) M6i pin g6m dien cuc la nhfing vat chi thi dOng dien gicia pin va m6i trvong xung quanh Mei dien chic dri6c nhung chim vao mot chat dien phan (thriong dung dich milk) cila moi niia phan iing Cac dien civic có the tham gia phan iing hoac chi a dan truy6n dien tich Dien civic anod la dien ctic ma xay ski Ox; electron cho di va rai dien cuc Dien civic catod la dien clic xay ski Kh; electron vao dien ctic va dvqc nhan 136i chat bi Kh 2 PIN GALVANIC Day la nhiing pin sii dung cac phan iing tri phat de tao dien nang 2.1 Cgu tao, hoat dong va sd do pin Galvanic 2.1.1 Pin Kern-bong - Khi rihring kern vao dung dich chlia ion Cu', mau xanh dm dung dich nhat clan vi Cu' chuye'n Cu kim loaf, Zn mon di tan vao dung dich dried clang ion Zn' Ta noi, Zn de bi oxy hod va |
