Common Ion Effect Calculator
Calculate how common ions affect pH and ionization equilibrium
Common Ion Effect
pH (without common ion)
2.8724
pH (with common ion)
4.4437
pH Change
+1.5713
% Ionization (without)
1.3416%
% Ionization (with)
0.0360%
Ionization Suppressed by:
97.32%
pKa: 4.7447
Understanding the Common Ion Effect
The common ion effect occurs when a salt containing an ion in common with the dissolved acid or base is added to a solution. According to Le Chatelier's principle, adding the common ion shifts the equilibrium to the left, suppressing ionization and changing the pH. This effect is the basis for buffer solutions and is important in solubility equilibria.