Question

The concentration of $\left[ H ^{+}\right]$and concentration of $\left[ OH ^{-}\right]$of a $0.1 M$ aqueous solution of $2 \%$ ionised weak monobasic acid is
[ionic product of water $=1 \times 10^{-14}$ ]

• A. $ 0.02 \times 10^{-3} M $ and $ 5 \times 10^{-11} M$
• B. $ 1 \times 10^{-3} M $ and $ 3 \times 10^{-11} M$
• C. $ 2 \times 10^{-3} M $ and $ 5 \times 10^{-12} M$
• D. $ 3 \times 10^{-2} M $ and $ 4 \times 10^{-13} M$

Answer 1

Answer: (C)

$\left[ H ^{+}\right]$in monobasic acid
= molarity $\times$ degree of ionisation
$=0.1 \times \frac{2}{100}=2 \times 10^{-3} M$
ionisation constant of water
$K_{w}=\left(H^{+}\right)\left(O H^{-}\right)$
$\left[O H^{-}\right]=\frac{1 \times 10^{-14}}{2 \times 10^{-3}}=5 \times 10^{-12} M$