Determine whether the solution is a strong acid, strong base, weak acid, or weak base
For a strong acid, use pH = -log[H+]
For a strong base, find pOH = -log[OH-], then pH = 14 – pOH
For a monoprotic strong acid, [H+] = molarity
For a monoprotic strong base, [OH-] = molarity
For a polyprotic acid or base, account for the number of H+ or OH- ions released per molecule
For a weak acid, use the acid dissociation constant Ka and an ICE table
For a weak base, use the base dissociation constant Kb and an ICE table
If needed, calculate [H+] or [OH-] from equilibrium before finding pH
Use pH = -log[H+]
Use pOH = -log[OH-]
Use pH + pOH = 14 at 25°C
If the solution is neutral, pH = 7
If the concentration is very low, consider water autoionization effects