Weak acids and bases can have a dual behavior. Let’s take the case of a weak acid. It can behave in two ways:
SITUATION 1. Weak acids in water are partially dissociated; they are weak.
SITUATION 2. On the other hand, when a strong base is added to the weak acid, this acid dissociates completeley, behaving like a strong acid. The explanation, according to Le Châtelier’s Principle, is that the hydroxide ions from the base reacts with the hydronium ions produced by the weak acid, shifting the equilibrium to the side of products.