Write an equation for each acid or base showing its ionization in water, and write the equilibrium constant expression for the weak acid or base. Nitrous Acid, HNO2Ka = 4.0 x 10-4Acetic Acid, HC2H3O2Ka

HNO₂ (aq) + H₂O (l) ⇄ H₃O⁺ (aq) + NO₂⁻ (aq)

Ka = [ H₃O⁺]. [NO₂⁻] / [HNO₂]

CH₃COOH (aq) + H₂O (l) ⇄ CHCOO⁻ (aq) + H₃O⁺ (aq) Ka

Ka = [CHCOO⁻]. [H₃O⁺] / [CH₃COOH]

Remember to add the autoinization of water:

2H₂O (l) ⇄ OH⁻ (aq) + H₃O⁺ (aq) Kw

Explanation:

Nitrous acid → HNO₂ (weak acid)

The ionization in water is:

HNO₂ (aq) → H⁺ (aq) + NO₂⁻ (aq)

Let's write the equilibrium:

HNO₂ (aq) + H₂O (l) ⇄ H₃O⁺ (aq) + NO₂⁻ (aq) Ka

Ka = [ H₃O⁺]. [NO₂⁻] / [HNO₂]

Acetic acid → CH₃COOH (weak acid)

Ionization in water: CH₃COOH (aq) → CHCOO⁻ (aq) + H⁺ (aq)

Equilibrium: CH₃COOH (aq) + H₂O (l) ⇄ CHCOO⁻ (aq) + H₃O⁺ (aq) Ka

Ka = [CHCOO⁻]. [H₃O⁺] / [CH₃COOH]