Question

The hydrogen ion concentration of a $10^{-8}\, M\, HCl$ aqueous solution at $298 \,K(K_w = 10^{-14})$ is

• A. $9.525 \times 10^{-8}\,M$
• B. $1.0 \times 10^{-8}\,M$
• C. $1.0 \times 10^{-6}\,M$
• D. $1.0525 \times 10^{-7}\,M$

Answer 1

Answer: (D)

$\therefore K_{w}=\left[H^{+}\right]\left[OH^{-}\right]$
or $10^{-14}=\left(10^{-8}+\alpha\right)\times\alpha$
$\Rightarrow \alpha=0.95\times10^{-7}$
$\therefore \, \left[H^{+}\right]=10^{-8}+0.95\times10^{-7}$
$=1.05\times10^{-7}\,M$