Question

At ${90}^{o}C$, pure water has $\left[H_3{O}^{\oplus }\right]={10}^{-6.7}mol{L}^{-1}$. What is the value of $K_w$ at ${90}^{o}C$?

• A. ${10}^{-6}$
• B. ${10}^{-12}$
• C. ${10}^{-13.4}$
• D. ${10}^{-6.7}$

Answer 1

The correct option is C ${10}^{-13.4}$

At ${90}^{o}C$, pure water has $\left[H_3{O}^{\oplus }\right]={10}^{-6.7}mol{L}^{-1}$ and $\left[O{H}^{-}\right]={10}^{-6.7}$

So $K_w=\left[H^{+}\right]\left[O{H}^{-}\right]={10}^{-6.7}\times {10}^{-6.7}={10}^{-13.4}$