To help you further Chemistry document serve the needs of learning and research, invite you to refer to the content of the curriculum lecture 2 "Acid-base equilbrium: Cân bằng axit-bazơ". Contents of lectures presented in: Acid base equilibrium, buffer solution, Acid-base titration, dissociation of acid. Hope lecture content is useful references for you. | Lecture 2 Acid-base equilbrium -Cân bằng axit-bazơ Contents Acid base equilibrium: Ka, Kb, Kw, calculate pH of solutions Buffer solution: Definition – Định nghĩa, prepare solution – cb dung dịch Acid-base titration: chuẩn độ Determine acidity in vinegar – xác định nồng độ axit trong dấm Acid-base reactions: Acid: Proton donor; Base: Proton acceptor Acid/Base conjugate pair: CH3COOH/CH3COO-; NH3/NH4+ Acid Base H+ Base Acid Dissociation of acid, Ka Dissociation of base, Kb Acid Dissociation Constant (Ka) Values at 25 oC Acid dissociation coefficient Table Acid Formula Ka Acid Formula Ka Hydroflouric HF ×10-4 Hydrocyanic HCN ×10-10 Formic HCOOH ×10-4 Carbonic H2CO3 ×10-7 ×10-11 Lactic H3CCH(OH)COOH ×10-4 Phosphoric H3PO4 ×10-3 ×10-8 ×10-13 Benzoic C6H5COOH ×10-5 Oxalic H2C2O4 ×10-2 ×10-5 Acetic H3CCOOH ×10-5 Hypochlorous HOCl ×10-8 Ka, Kb are constant at a certain temperature and pressure. Ka, Kb represent the strength of acid and base. The . | Lecture 2 Acid-base equilbrium -Cân bằng axit-bazơ Contents Acid base equilibrium: Ka, Kb, Kw, calculate pH of solutions Buffer solution: Definition – Định nghĩa, prepare solution – cb dung dịch Acid-base titration: chuẩn độ Determine acidity in vinegar – xác định nồng độ axit trong dấm Acid-base reactions: Acid: Proton donor; Base: Proton acceptor Acid/Base conjugate pair: CH3COOH/CH3COO-; NH3/NH4+ Acid Base H+ Base Acid Dissociation of acid, Ka Dissociation of base, Kb Acid Dissociation Constant (Ka) Values at 25 oC Acid dissociation coefficient Table Acid Formula Ka Acid Formula Ka Hydroflouric HF ×10-4 Hydrocyanic HCN ×10-10 Formic HCOOH ×10-4 Carbonic H2CO3 ×10-7 ×10-11 Lactic H3CCH(OH)COOH ×10-4 Phosphoric H3PO4 ×10-3 ×10-8 ×10-13 Benzoic C6H5COOH ×10-5 Oxalic H2C2O4 ×10-2 ×10-5 Acetic H3CCOOH ×10-5 Hypochlorous HOCl ×10-8 Ka, Kb are constant at a certain temperature and pressure. Ka, Kb represent the strength of acid and base. The smaller the Ka (Kb) : the weaker the acid (base). Monoprotic acid: one acidic proton, HCl, HNO3, CH3COOH Monoprotic base: NaOH, NH4OH Polyprotic acid: more than one acidic proton, H3PO4, H2SO4 Polyprotic base: Cu(OH)2, Fe(OH)3, Dissociation of water Dissociation of water Water dissociation coefficient Kw varies with temperature, at 200C Kw = ×10-15; at 300C Kw = ×10-14 pH = -log[H+] ; pOH = -log[OH-] (ignoring activity correction) pH + pOH = 14 (to the extent that Kw = 1×10-14) For neutral solution: pH =pOH =7 (at 250C) Acidic solution: pH 7 Ka,Kb of conjugate acid/base pair Dissociation of CH3COOH CH3COOH + H2O CH3COO- + H3O+ (1) Ka CH3COO- + H2O CH3COOH + OH- (2) Kb (1) + (2) gives: 2H2O H3O+ + OH- So KaKb =Kw = 10-14 Or pKa + pKb = 14. * Example: Ka,CH3COOH = ; Find Kb, CH3COO- =? Kb,NH3 = , Find Ka,NH4+ = ? Exercise Calculating pH What’s pH of solution of M HCl; 10-7 M HCl? What’s pH of M NaOH solution? What’s pH
