Question

At ${90}^{\circ }C$, the concentration of hydronium ion in pure water has ${10}^{-6}{\text{molL}}^{-1}$. what is the value of $K_w$ at ${90}^{\circ }C$

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

Answer 1

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

Given, concentration of hydronium ion, $\left(\right[H_3{O}^{+}\left]\right)$ is ${10}^{-6}{\text{molL}}^{-1}$.
For pure water, $\left[H_3{O}^{+}\right]=\left[O{H}^{-}\right]$
So, $K_w={10}^{-6}\times {10}^{-6}={10}^{-12}$