Question

HX is a weak acid $(K_a={10}^{-5})$. It forms a salt NaX (0.1 M) 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

Answer: (A)

0.01 %

$NaX$ is a weak acid -strong base salt.

So, hydrolysis $h=\sqrt{\frac{K_h}{C}}=\sqrt{\frac{K_w}{K_a\times C}}=\sqrt{\frac{{10}^{-14}}{{10}^{-5}\times 0.1}}={10}^{-4}$

So, % hydrolysis $=0.01$