北京化工大学：《无机化学》课程电子教案（课件讲稿，2015）Chapter 8 Acid-Base Equilibrium

Chapter 8 Acid-Base Equilibrium ק8.1 The Bronsted theory of acids and bases ק8.2 Ionization equilibrium of water and the pH scale X 8.3 Equilibrium in solutions of weak acids and weak bases X 8.4 Buffer solutions

Chapter 8 Acid-Base Equilibrium § 8.4 Buffer solutions § 8.3 Equilibrium in solutions of weak acids and weak bases § 8.2 Ionization equilibrium of water and the pH scale § 8.1 The Brønsted theory of acids and bases

8.5 Acid-bases indicators X 8.6 Lewis acids and bases and coordination compounds X 8.7 Complexation reaction and coordination equilibrium

§ 8.7 Complexation reaction and coordination equilibrium § 8.6 Lewis acids and bases and coordination compounds § 8.5 Acid-bases indicators

8.1 The Bronsted theory of acids and bases 8.1.1 The Bronsted acids and bases 8.1.2 Relative strengths of acids and bases

§ 8.1 The Brønsted theory of acids and bases 8.1.2 Relative strengths of acids and bases 8.1.1 The Brønsted acids and bases

Overview:(sour,bitter)Taste-→Arrhenius theory(酸碱电离理论， Ht&OHr),→Solvent theory,,Bronsted theory(质子理论)，Lewis theory(电子理论)，soft-hard acid/,base theory. 8.1.1 The Bronsted theory of acids and bases(酸碱质子理论) acid:a substance capable of donating a proton.(proton donor) (质子的给予体) base:a substance that can accept a proton.(proton acceptor) (质子的接受体)

acid: a substance capable of donating a proton. (proton donor) （质子的给予体） base: a substance that can accept a proton. (proton acceptor) （质子的接受体） 8.1.1 The Brønsted theory of acids and bases (酸碱质子理论） Overview: (sour, bitter) Taste Arrhenius theory(酸碱电离理论, H+&OH- ),  Solvent theory, Bronsted theory(质子理论), Lewis theory(电子理论), soft-hard acid/base theory…

an acid 土 H++a base HAc =H*+Ac H2PO-H*+HPO2 HPO-H*+PO NH-H*+NH3 [CH:NH3]*=H*+CH3NH2 [Fe(H2O)]*-H*+[Fe(OH)(H2O);]2* [Fe(OH)(H2O);]2*-H*+[Fe(OH)2(H2O)aT conjugate acid conjugate base an acid-base conjugate pair(共轭酸碱对)

an acid H+ + a base + - HAc H + Ac - + - + 2 H2PO 4 H HPO 4 - + - + 3 4 2 HPO 4 H PO + + + NH 4 H NH 3 [ ] + + + CH 3NH 3 H CH 3NH 2 + + + + 2 2 5 3 [Fe(H 2O) 6 ] H [Fe(OH)(H O) ] + + + + 2 2 4 2 [Fe(OH)(H 2O) 5 ] H [Fe(OH) (H O) ] conjugate acid conjugate base an acid-base conjugate pair (共轭酸碱对)

amphiprotic substance(两性物质)： a substance that can either donate or accept a proton is said to be amphiprotic. Example:HSO,[Fe(OH)(H2O)s]2,HCO3,H2O,HS etc the essence of acid-base reaction in Bronsted theory is proton transfer between two acid-base conjugate pairs,examples are given below:

amphiprotic substance(两性物质)： a substance that can either donate or accept a proton is said to be amphiprotic. HCO3 - , H2O, HS- [Fe(OH)(H etc 2O)5 ] 2+ HSO , 4 - Example: , the essence of acid-base reaction in Brønsted theory is proton transfer between two acid-base conjugate pairs, examples are given below:

1 The ionization reactions of acids and bases in solvent are proton-transfer reactions. Example:the ionization of HF in water can be represented as HF(aq)=H++F(aq) H++H2O)=H30*(aq) HF(aq)+H2O(1)=H3O(aq)+F(aq) 2Water is an amphiprotic substance,its autoionization is also proton-transfer reaction. H H20)+H20)=H30(aq)+OH-(aq) acid(1) base(2) acid(2) base(1)

① The ionization reactions of acids and bases in solvent are proton-transfer reactions. Example: the ionization of HF in water can be represented as ② Water is an amphiprotic substance, its autoionization is also proton-transfer reaction. H+ acid(1) base(2) acid(2) base(1) HF(aq) H+ + F－(aq) H+ + H2O(l) H3O+ (aq) HF(aq) + H2O(l) H3O+ (aq) + F－(aq) H2O(l)+H2O(l) H3O+ (aq) +OH－(aq)

③The hydrolysis of salts(no“salt”term in Brensted theory)can be regarded as proton-transfer reactions of acids and bases.Example:the hydrolysis of NaAc H+ Ac-+H,O-OH+HAc base(1)acid(2)base(2 )acid(1) the hydrolysis of NHCl: H NH:+H2O=H2O++NH; acid(1)base(2) acid(2) base(1)

③ The hydrolysis of salts (no “salt” term in Brønsted theory) can be regarded as proton-transfer reactions of acids and bases. Example: the hydrolysis of NaAc base(1) acid(2) base(2) acid(1) H+ the hydrolysis of NH4Cl： acid(1) base(2) acid(2) base(1) H+ Ac－+H2O OH－ + HAc + H2O H3O+ + NH3 + NH4

4The acid-base reactions in non-aqueous solution can also be regarded as proton-transfer reactions.Example: the formation reaction of NHCl: H HCI+ NH NH C1- acid(1) base(2) acid(2) base(1) the neutralization reaction in liquid ammonia H NH CI+NaNH, 2NH,NaCl acid(1) base(2) acid(2)+base(1)

④ The acid-base reactions in non-aqueous solution can also be regarded as proton-transfer reactions. Example: the formation reaction of NH4Cl： H+ the neutralization reaction in liquid ammonia ： H+ + - HCl + NH NH + Cl 3 4 NH Cl NaNH 2NH NaCl 4 + 2 3 + acid(1) base(2) acid(2) base(1) acid(1) base(2) acid(2) + base(1)

8.1.2 Relative strengths of acids and bases The strength of an acid or a base refers to the ability of donating proton for an acid or accepting proton for a base. HAc HCN HCI,HNO3 K3 1.8×10-5 5.8×10-10 H-Cl: differentiating effect(区分效应)： e.g.:H2O can differentiate the relative strength of HAc,HCN. leveling effect(拉平效应)：a solvent's ability to level the effect of a strong acid or base dissolved in it

HAc HCN differentiating effect(区分效应)： e.g.：H2O can differentiate the relative strength of HAc，HCN. leveling effect(拉平效应)：a solvent's ability to level the effect of a strong acid or base dissolved in it. The strength of an acid or a base refers to the ability of donating proton for an acid or accepting proton for a base. 8.1.2 Relative strengths of acids and bases 1.8×10 K -5 a 5.8×10-10 HCl， HNO3