Question

$HClO$ is a weak acid. The concentrations of $\left[H^{+}\right]$ ions in $0.1M$ solution of $HClO(K_a=5\times {10}^{-8})$ will be equal to:

• A. $7.07\times {10}^{-5}M$
• B. $5\times {10}^{-7}M$
• C. $6\times {10}^{-7}M$
• D. $7\times {10}^{-4}M$

Answer 1

The correct option is A

$7.07\times {10}^{-5}M$

$\left[H^{+}\right]=c\alpha =\sqrt{\left[\frac{K_a}{c}\right]=}\sqrt{K_{a}c}=\sqrt{5\times {10}^{-8}\times 0.1}$
$=7.07\times {10}^{-5}M$