The degree of hydrolysis of a specific salt formed from a weak acid and a weak base is experimentall — Ionic Equilibrium Chemistry Question
Question
The degree of hydrolysis of a specific salt formed from a weak acid and a weak base is experimentally found to be exactly $50\%$ when its concentration is $0.1 \text{ M }$. If the solution is further concentrated by evaporation at constant temperature until its molarity becomes $0.2 \text{ M }$, what will be its exact percentage degree of hydrolysis?
💡 Solution & Explanation
For a salt derived from a weak acid and a weak base, the degree of hydrolysis ($h$) is determined by the equation $\frac{h^2}{(1-h)^2} = K_h = \frac{K_w}{K_a \cdot K_b}$. Because the concentration term ($C$) cancels out entirely from the equilibrium expression, the degree of hydrolysis remains absolutely independent of the salt's initial concentration. Thus, it remains $50\%$.