Abstract
The calculus of the acid-base equilibria can be rationalized by applying the proton condition or the hydroxyl condition in every case, on solutions of strong bases, mixtures of bases, mixtures of acids and bases, and different salts. Furthermore, applying the proton condition or the hydroxyl condition in equilibrium, it is clearly pointed out that the hydroxyls in equilibrium are additive in solutions of strong bases as well as in those of weak bases.