# What is the pH of a solution with a concentration of 2.4*10^-5 molar H_3O^+?

$p H$ $=$ $- {\log}_{10} 2.4 \times {10}^{- 5}$.
$p H$ $=$ $- {\log}_{10} \left[{H}_{3} {O}^{+}\right]$.