I neutralt vatten:
\[\begin{aligned}\mathrm{[H^+]} &= \mathrm{[OH^-]} \\ \mathrm{pH} &= \mathrm{pOH} \\ \mathrm{p}K_\mathrm{w} &= \mathrm{pH + pOH} = \mathrm{pH + pH} = 2\mathrm{pH} \\ \mathrm{pH} &= \frac {\mathrm{p}K_\mathrm{w}}{2} = \frac {13,54}{2} = 6,77\end{aligned}\]
