Surface thermodynamics reconsidered. Derivation of the Gokhshtein relations from the Gibbs potential and a new approach to surface stress

The terminology and definition of surface tension are discussed. In particular, the surface tension is defined as the partial derivative of the surface excess Gibbs energy with respect to an infinitesimal increment of surface area at constant temperature and pressure. The surface tension is also formulated as the sum of a stress-free component and a stress-containing component. The stress-containing component is defined as the surface stress. Finally, the case of charged surfaces is analyzed, and the Gokhshtein relations are derived from the Gibbs potential in the special case that the electrode/solution interface is ideally polarizable.