Question

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

Answer 1

`10^(-6)` mol per litre

Explanation:

`pH` is `-log_10` of the hydrogen ion concentration (actually hydronium `H_3O^+` concentration).

`pOH` is `-log_10` of the hydroxyl (`OH^-`) ion concentration.

To say `pH + pOH = 14` is to say that the product of the `H_3O^+` and `OH^-` ion concentrations is `10^-14`.

If a solution has `pH = 8`, then its `pOH` is `14-8 = 6` and the corresponding concentration of hydroxyl `OH^-` ions is `10^(-6)` mol per litre.