The pH of a solution can be calculated using which formula?

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