1. Weak Acids A weak acid does not ionize completely to form hydrogen ions. e.g.HC 2 H 3 O 2 (aq ) H + (aq) + C 2 H 3 O 2 - (aq) 1.3% K a = [H + (aq) ] [H + (aq) ] [HC 2 H 3 O 2 (aq) ]

2. Weak Bases A weak base has a weak attraction for protons. e.g. NH 3 (aq) + H 2 O (l) NH 4 + (aq) + OH – (aq) K b = [NH 4 + (aq) ] [OH - (aq) ] [NH 3 (aq) ]

3. For a conjugate acid-base pair: K a K b = K w Therefore: 1. The conjugate base of a strong acid is a very weak base. 2. The conjugate base of a very weak acid is a strong base. 3. The conjugate base of a weak acid is a weak base.