Question

$HX$ is a weak acid $(K_a={10}^{-5})$. It forms a salt $NaX\left(0.1M\right)$ on reacting with caustic soda. The degree of hydrolysis of $NaX$ is:

• A. 0.01%
• B. 0.0001%
• C. 0.1%
• D. 0.5%

Answer 1

The correct option is A 0.01%

$K_h\left(X^{-}\right)=\frac{K_w}{K_a}=\frac{{10}^{-14}}{{10}^{-5}}={10}^{-9}$
$\Rightarrow \alpha =\sqrt{\frac{K_h}{C}}=\sqrt{\frac{{10}^{-9}}{0.10}}={10}^{-4}$
$\therefore$ % hydrolysis $=100\alpha =0.01$