HCl is a strong acid. What is the pH of 200 mL of 0.002 M HCl?

1 Answer
Feb 6, 2017

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

Explanation:

$\text{Hydrochloric acid}$, as a strong acid, is stoichiometric in ${H}_{3} {O}^{+}$. And thus:

$p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right] = - {\log}_{10} \left(0.002\right) = - \left(- 2.70\right) = 2.70$

Note that the $p H$ thus depends on concentration solely. And thus what would be the $p H$ of a $2 \cdot L$ volume of $2 \times {10}^{-} 3 \cdot m o l \cdot {L}^{-} 1$ $\text{hydrochloric acid}$?