18.2 Calculations involving acids and bases
Essential Idea:
The equilibrium law can be applied to acid–base reactions. Numerical problems can be simplified by making assumptions about the relative concentrations of the species involved. The use of logarithms is also significant here.
Understandings:
- The expression for the dissociation constant of a weak acid (Ka) and a weak base (Kb).
- For a conjugate acid base pair, Ka× Kb = Kw.
- The relationship between Ka and pKa is (pKa = -log Ka), and between Kb and pKb is (pKb = -log Kb).
Applications and Skills:
- Solution of problems involving [H+ (aq)], [OH–(aq)], pH, pOH, Ka, pKa, Kb and pKb.
- Discussion of the relative strengths of acids and bases using values of Ka, pKa, Kb and pKb.