Ionic Equilibrium and pH

Weak acids partially dissociate: HA ⇌ H⁺ + A⁻. Ka = [H⁺][A⁻]/[HA]. pH = -log[H⁺]. pOH = -log[OH⁻]. pH + pOH = 14 at 25°C. Strong acids: HCl, H₂SO₄, HNO₃ (fully dissociate). Weak acids: CH₃COOH, H₂CO₃ (partially dissociate). Buffer: resists pH change (weak acid + its salt).