Question

At ${90}^{\circ }\text{C}$, pure water has $\left[H^{+}\right]={10}^{-6}\text{M}$. The value of $K_w$ at ${90}^{\circ }\text{C}$ is ____

• A. ${10}^{-6}{\text{M}}^2$
• B. ${10}^{-8}{\text{M}}^2$
• C. ${10}^{-12}{\text{M}}^2$
• D. ${10}^{-14}{\text{M}}^2$

Answer 1

The correct option is C ${10}^{-12}{\text{M}}^2$

At ${90}^{\circ }\text{C}$, pure water has $\left[H^{+}\right]={10}^{-6}\text{M}.$
In pure water, $\left[H_3{O}^{+}\right]=\left[O{H}^{-}\right]$
The value of $K_w$ at ${90}^{\circ }\text{C}$, $K_w=\left[H_3{O}^{+}\right]\left[O{H}^{-}\right]={10}^{-6}\times {10}^{-6}={10}^{-12}{\text{M}}^2$