CHEMISTRY 161

Chapter 4

REVISION

1. solution, solvent, and solute

2. experimental definition of strong/weak/non-electrolyte

3. dissociation and hydration of solute in solvent

(solutions conduct electricity)

4. precipitation reaction

(molecular equation, ionic equation, spectator ions)

CHEMICAL REACTIONS

1.properties of solutions

2. reactions in solutions

a) precipitation reactions

b) acid-base reactions (proton transfer)

c)redox reactions (electron transfer)

2.2. ACIDS AND BASES

Arrhenius (1883)

ACIDS

BASES

NaOH (s) → Na+ (aq) + OH- (aq)

MOH → M+ (aq) + OH- (aq)

HCl (g) → H+ (aq) + Cl- (aq)

HAc → H+ (aq) + Ac- (aq)

ACIDS

1. acids have a sour taste

vinegar – acetic acidlemons – citric acid

2. acids react with some metals to form hydrogen

2 HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)

3. acids react with carbonates to water and carbon dioxide

2 HCl(aq) + CaCO3(s) → CaCl2(aq) + [H2CO3]H2CO3 → H2O(l) + CO2(g)

BASES

1. bases have a bitter taste

2. bases feel slippery

soap

3. aqueous bases and acids conduct electricity

Bronsted (1932)

ACIDS

HAc → H+ (aq) + Ac- (aq)

proton donors

BASES

proton acceptor

B + H+ (aq) → BH+ (aq)

H+ ≈ 10-15 m

Na+ ≈ 10-10 m

(aq) (l) (aq) (aq)

hydronium ion

acid base

cation hydronium ion

weak electrolyte

CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq)

NH3(aq) + H2O(l) NH4+ + OH-

strong electrolyte

HCl(aq) + H2O(l) → H3O+(aq) + Cl-(aq)

HNO3(aq) + H2O(l) → H3O+(aq) + NO3-(aq)

monoprotic acids

CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq)

NH3(aq) + H2O(l) NH4+(aq)+ OH-(aq)

H2O(l) + H2O(l) H3O+(aq) + OH-(aq)

water can be either an acid or a base

monoprotic acids

diprotic acid

HF, HCl, HBr, HNO3, CH3COOH

H2SO4 → H+(aq) + HSO4-(aq)

HSO4-(aq) H+(aq) + SO4

2-(aq)

triprotic acid

H3PO4 H+(aq) + H2PO4-(aq)

H2PO4-(aq) H+(aq) + HPO4

2-(aq)

HPO42-(aq) H+(aq) + PO4

3-(aq)

Acids in the Solar System

Venus

H2SO4(g)

Europa

H2SO4(s)

Acids in the Interstellar Medium

Orion

NH3, H2O, H2S

CH3COOH

HCOOH

HF, HCl

ACID-BASE REACTION

acid + base → salt + water

(neutralization reaction)

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

molecular equation – ionic equation – spectator ions

SUMMARY

1.acids and bases

1.1. Arrhenius and Bronsted

1.2. strong and weak acids and bases

1.3 acids in extraterrestrial environments

2. acid-base neutralization reactions

Homework

Chapter 4, p. 111-116problems