Adding a common ion to a system at equilibrium affects the equilibrium composition but not the ionization constant.

Question

Quizplus · Accepted Answer

Adding a common ion to a system at equilibrium decreases the solubility of a slightly soluble salt or decreases the ionization of a weak acid or base. This leads to a shift in equilibrium towards the formation of the less soluble salt or weaker acid or base. However, the ionization constant (K) remains the same because it is a characteristic property of the acid or base and not affected by the presence of common ions.

Adding a Common Ion to a System at Equilibrium Affects