Question

At ${90}^{o}C$ pure water has $\left[H_3{O}^{+}\right]={10}^{-6}$ $mol/litre$. The value of $K_w$ at ${90}^{o}C$ is

• A. ${10}^{-6}$
• B. ${10}^{-12}$
• C. ${10}^{-8}$
• D. ${10}^{-14}$

Answer 1

The correct option is B ${10}^{-12}$

For pure water, $\left[H^{+}\right]=\left[{OH}^{-}\right]$
and

$K_w=\left[H^{+}\right]\left[{OH}^{-}\right]={\left[H^{+}\right]}^2={\left[{10}^{-6}\right]}^2={10}^{-12}$