ABSTRACT
Interfacial free energy or interfacial tension is the excess free energy due to the existence of an interface arising from the unbalanced molecular forces. This chapter presents an example which illustrates the dependence of interfacial phenomena on bulk solubility. A dissolved component in a mixture may demonstrate “surface activity” by reducing the interfacial free energy of the solvent and by creating an excess concentration at the interface. The energy of the interphase relative to the ideal gas state was calculated by subtracting the change in energy on forming the surface phase from pure liquid, from the energy of the bulk liquid relative to the ideal gas. Properties of the interfaces could be determined by assuming that the interphase was a regular solution and defining a surface cohesion parameter as the square root of the surface cohesive energy. An important group of practical surface properties involve ‘ Vetting” and “dewetting”
