Abstract
It is shown that stoichiometric rather than thermodynamic dissociation constants can and should be used in the buffer capacity theory. The mean valence of bivalent weak acids and bases is deduced in a form with dimensionless parameters. The expressions for the molar buffer capacities of bivalent weak acids and bases are identical with that for a bivalent ampholyte, and the theory for the latter given earlier is thus valid in all details for bivalent weak acids and bases.