Question

In the hydrolytic equilibrium $A^{-}+H_{2}O\rightleftharpoons HA+{OH}^{-}$, $K_a=1.0\times {10}^{-5}$. The degree of hydrolysis of $0.001M$ solution of the salt is:

• A. ${10}^{-3}$
• B. ${10}^{-4}$
• C. ${10}^{-5}$
• D. ${10}^{-6}$

Answer 1

The correct option is A ${10}^{-3}$

Salts are strong electrolytes when dissolved in water will dissociate and form acids and bases with $H^{+}$ and $O{H}^{-}$ ions.

$K_a={10}^{-5},C=0.001M$

Degree of hydrolysis is :

$h=\sqrt{\frac{K_w}{K_a\times C}}=\sqrt{\frac{{10}^{-14}}{{10}^{-5}\times 0.001}}=\sqrt{{10}^{-14+5+3}}={10}^{-3}\Rightarrow h={10}^{-3}$