# What is the pH of a 0.090 M HCl solution?

$p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$, so.........
$H C l \left(a q\right) + {H}_{2} O \left(l\right) \rightarrow {H}_{3} {O}^{+} + C {l}^{-}$
And thus $p H = - {\log}_{10} \left(0.090\right)$ $=$ $- \left(- 1.05\right)$ $=$ $1.05$.
What is $p O H$ of this solution?