# What is the pH of concentrated HCl(aq)?

Jul 16, 2016

Less than $- 1$, but don't quote me.
$p H = - {\log}_{10} \left(\left[{H}_{3} {O}^{+}\right]\right) .$
Thus $p H = - {\log}_{10} \left(12\right)$, which value is less than $- 1$.
The commercial reagent 37% $\frac{m}{m}$ is approx. $12 \text{ molar}$.