Question

What will be the $H^{+}$ ion concentration of 0.01 M $HCN$ solution at equilibrium, if it is 20% ionised?

• A. $2\times {10}^{-3}M$
• B. $3\times {10}^{3}M$
• C. $5\times {10}^{3}M$
• D. $1\times {10}^{3}M$

Answer 1

The correct option is A $2\times {10}^{-3}M$

$HCN\left(aq\right)\rightleftharpoons H^{+}(aq.)+C{N}^{-}(aq.)Initial:C00Equilibrium:C(1-\alpha )C\alpha C\alpha$
C =$0.01M={10}^{-2}M$
$\alpha$ % = 20%
$\alpha$= 0.2
$\left[H^{+}\right]=C\alpha$
$\left[H^{+}\right]={10}^{-2}\times 0.2$
$\left[H^{+}\right]=2\times {10}^{-3}M$