Select the statement that correctly explains why it is reasonable to assume that for a weak acid, [HA] at equilibrium is approximately equal to [HA]init under most circumstances. Multiple choice question. The weak acid and its conjugate base are so similar that acid ionization can be ignored. Most molecules of the weak acid remain unionized at equilibrium. A weak acid has a high pH. Since the concentration of a weak acid is usually high, it remains essentially unchanged in the reaction