Question

A weak acid $HX$ has the dissociation constant $1\times {10}^{-5}M$. It forms a salt $NaX$ on reaction with alkali. The percentage hydrolysis of $0.1$ M solutions of $NaX$ is:

• A. $0.0001$%
• B. $0.01$%
• C. $0.1$%
• D. $0.15$%

Answer 1

Answer: (B)

$0.01$%

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

So, hydrolysis of $NaX$ will be

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

Therefore, % hydrolysis will be $={10}^{-4}\times 100=0.01\%$