Question

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

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

Answer 1

Answer: (A)

Use the following formula to find concentration of $ OH^{-} $ ions.
$\left[H^{+}\right]=C \alpha$
$\left[O H^{-}\right]=\frac{\text { ionic product of water }}{\left[H^{+}\right]}$
Given, $C=0.1$
$\alpha=2$
$\left[H^{+}\right]=C \alpha$
$=0.1 \times 0.01$
$=2 \times 10^{-3}$
$\left[O H^{-}\right]=\frac{1 \times 10^{-14}}{2 \times 10^{-3}}$
$=5 \times 10^{-12}$