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. 0.000001
• B. 0.0001
• C. 0.001
• D. 0.0015

Answer 1

Answer: (B)

0.0001

Answer 2

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