Question

The degree of hydrolysis of a salt of weak acid and weak base in it's 0.1 M solution is found to be 50%. If the molarity of the solution is 0.2 M, the percentage hydrolysis of the salt should be

• A. 100%
• B. 50%
• C. 25%
• D. none of these

Answer 1

Answer: (B)

50%

Answer 2

The degree of hydrolysis ($h$) for a salt of a weak acid and a weak base is related to the hydrolysis constant ($K_h$) by the equation $K_h = \frac{h^2}{(1-h)^2}$. This equation shows that the degree of hydrolysis ($h$) is independent of the concentration ($C$) of the salt solution. Therefore, if the degree of hydrolysis is 50% at 0.1 M concentration, it will remain 50% at 0.2 M concentration, or any other concentration, provided the temperature is constant.