There are quite a few
relationships between [H+] and [OH−]
ions. And because there is a large range of number between 10 to 10-15
M, the pH is used. pH = -log[H+] and pOH = -log[OH−]. In aqueous solutions, [H+
][OH- ] = 10-14. From here we can derive the values of each concentration.
-log[H+ ] + -log[OH- ] = -log[10-14]
pH + pOH = 14
So pH = 14 – pOH and pOH = 14 –
pH
A neutral solution occurs when pH
= pOH = 7. It is an acid solution when [H+ ] > [OH- ], pH < 7 and basic when [H+ ] < [OH- ], pH
> 7.
