Question

The hydrogen ion concentration of a $10^{-8}MHCl$ aqueous solution at $298K(K_w=10^{-14})$ 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)

$\therefore K_w=\left[H^{+}\right]\left[O{H}^{-}\right]$
or $10^{-14}=\left(10^{-8}+\alpha \right)\times \alpha$
$\Rightarrow \alpha =0.95\times 10^{-7}$
$\therefore \left[H^{+}\right]=10^{-8}+0.95\times 10^{-7}$
$=1.05\times 10^{-7}M$