# What is the pH of a 8.7*10^-12 M solution?

I assume that $\left[{H}_{3} {O}^{+}\right] = 8.7 \times {10}^{- 12}$ in water under standard conditions.
In aqeuous solution, $p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$
$=$ $- {\log}_{10} \left(8.7 \times {10}^{-} 12\right)$ $=$ $- \left(- 11.06\right)$ $=$ $11.1$