Interfacial potentials at the interface between two immiscible electrolyte solutions: Some problems in definitions and interpretation

Some problems concerning definition and calculation of the interfacial potential difference at the interface between two immiscible electrolyte solutions are discussed. Among them are the calculation of the distribution potential for an unsymmetrical electrolyte, which is proved to depend on electrolyte concentration, contrary to generally accepted opinion. Equations are presented for potential difference in the cases of Donnan equilibrium, of two electrolytes with a common ion, and of ion complexing in one of the phases. Finally, the equation for interfacial potential in the presence of a redox reaction at the interface between two immiscible liquids is derived. The novel notions of interfacial redox and mixed potentials are introduced.