Question

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

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

Answer 1

Answer: (B)

$X^{-}+ H _{2} O \rightleftharpoons HX + OH ^{-}$
$K_{h} =\frac{10^{-14}}{10^{-5}}$
So, degree of hydrolysis
$x=\sqrt{\frac{K_{h}}{C}}=\sqrt{\frac{10^{-9}}{10^{-1}}}=10^{-4}$
$\%$ degree of hydrolysis $=10^{-4} \times 100=0.01 \%$