CHEMISTRY 161 Chapter 4

REVISION 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 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 HAc → H+ (aq) + Ac- (aq) HCl (g) → H+ (aq) + Cl- (aq) BASES MOH → M+ (aq) + OH- (aq) Arrhenius (1883) NaOH (s) → Na+ (aq) + OH- (aq)

ACIDS acids have a sour taste vinegar – acetic acid lemons – 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 bases have a bitter taste 2. bases feel slippery soap 3. aqueous bases and acids conduct electricity

proton donors HAc → H+ (aq) + Ac- (aq) proton acceptor ACIDS proton donors HAc → H+ (aq) + Ac- (aq) BASES proton acceptor B + H+ (aq) → BH+ (aq) Bronsted (1932)

≈ 10-15 m H+ ≈ 10-10 m Na+

(aq) (l) (aq) (aq) acid base hydronium ion

cation hydronium ion

monoprotic acids strong electrolyte HCl(aq) + H2O(l) → H3O+(aq) + Cl-(aq) HNO3(aq) + H2O(l) → H3O+(aq) + NO3-(aq) weak electrolyte CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) NH3(aq) + H2O(l) NH4+ + OH- monoprotic acids

water can be either an acid or a base 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 triprotic acid HF, HCl, HBr, HNO3, CH3COOH diprotic acid H2SO4 → H+(aq) + HSO4-(aq) HSO4-(aq) H+(aq) + SO42-(aq) triprotic acid H3PO4 H+(aq) + H2PO4-(aq) H2PO4-(aq) H+(aq) + HPO42-(aq) HPO42-(aq) H+(aq) + PO43-(aq)

Acids in the Solar System Europa H2SO4(s) Venus H2SO4(g)

Acids in the Interstellar Medium

NH3, H2O, H2S CH3COOH HCOOH HF, HCl Orion

ACID-BASE REACTION HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) acid + base → salt + water (neutralization reaction) HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) molecular equation – ionic equation – spectator ions

SUMMARY 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. 111-116 problems