# What is the concentration of hydroxyl ions in a solution of pH 8 ?

Feb 5, 2018

${10}^{- 6}$ mol per litre

#### Explanation:

$p H$ is $- {\log}_{10}$ of the hydrogen ion concentration (actually hydronium ${H}_{3} {O}^{+}$ concentration).

$p O H$ is $- {\log}_{10}$ of the hydroxyl ($O {H}^{-}$) ion concentration.

To say $p H + p O H = 14$ is to say that the product of the ${H}_{3} {O}^{+}$ and $O {H}^{-}$ ion concentrations is ${10}^{-} 14$.

If a solution has $p H = 8$, then its $p O H$ is $14 - 8 = 6$ and the corresponding concentration of hydroxyl $O {H}^{-}$ ions is ${10}^{- 6}$ mol per litre.