Dynamic Potentials of Freshly Formed Liquid Surfaces

Abstract

As a basis for the study of the adsorption of a surface-active solute to a fresh liquid surface, it is necessary to establish with accuracy the changes in the physical properties of the surface which occur immediately after its formation, and throughout the adsorption process. Two important properties, which undergo considerable change as adsorption proceeds, are the surface tension and the surface potential. We have recently observed that the surface potential of aqueous solutions of many long-chain compounds, at the instant when adsorption is complete, differs widely from the ultimate equilibrium value. The changes in potential following establishment of concentration equilibrium between surface and bulk solution are comparable in magnitude with those occurring during adsorption, and erroneous deductions may result from the assumption that dynamic surface tensions and potentials change in a similar manner with age of surface.