AbstractThe acid‐base equilibria of oxalic, malonic and succinic acids, ethylenediamine, diethylenetriamine and glycine were studied potentiometrically (glass electrode) in NaClO4(for polyamines also in NaCl) solution of various concentrations (0.01‐3 M), at 25°C. The dependence of the change of equilibrium constants with ionic strength on the distance between charge centres in ion is discussed. This dependence more markedly exhibits for ions with the shortest distances between charge centres. No differences in observed effects for different classes of ions were found. The simulation of the medium effects for the systems involving ions with separated charge centres was carried out on the basis of electrostatic notion with the data on the ion structure and the magnitudes of charges on a