# What is the pH of an aqueous solution if the [H^+]=0.000001?

Oct 3, 2016

$p H = 6$

#### Explanation:

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

But if $\left[{H}^{+}\right]$ or $\left[{H}_{3} {O}^{+}\right]$ $=$ $0.000001 \cdot m o l \cdot {L}^{-} 1$;

then $p H$ $=$ $- {\log}_{10} \left(0.000001\right)$ $=$ $- {\log}_{10} \left({10}^{-} 6\right)$.

Now, by definition, ${\log}_{10} \left({10}^{-} 6\right)$ $=$ $- 6$.

Thus $p H = - \left(- 6\right)$ $=$ $6$

This is slightly acid, and $\left[{H}_{3} {O}^{+}\right]$ is $10 \times \left[H {O}^{-}\right]$.

If $\left[{H}_{3} {O}^{+}\right]$ $=$ $0.001 \cdot m o l \cdot {L}^{-} 1$, what is $p H$?