# An aqueous solution has a hydronium ion concentration of 6 * 10^-9 mole per liter at 25°C. What is its pH?

May 9, 2016

$p H = 8$

#### Explanation:

The pH of a solution could be calculated using the concentration of hydronium ${H}_{3} {O}^{+}$ by: $p H = - \log \left[{H}_{3} {O}^{+}\right]$

Therefore, $p H = - \log \left(6 \times {10}^{- 9}\right) = 8.22 = 8 \left(\text{1 significant figures}\right)$

Acids & Bases | Nature, Strength & pH Scale.

May 9, 2016

$p H = 8.22$

#### Explanation:

So what is $p H$?

Here it is simply the function $p H = - {\log}_{10} \left[{H}_{3} {O}^{+}\right]$, $p H$ derives from the French $\text{pouvoir hydrogene}$, $\text{the power of hydrogen}$.

We have $\left[{H}_{3} {O}^{+}\right]$ and we have a calculator, so we press the buttons.

It is worthwhile to review the logarithmic function, and see why the use of logarithms (and slide rules) was absolutely widespread among scientists and engineers in a pre-calculator world.