THE INFLUENCE OF DOUBLE LAYER STRUCTURE ON THE ADSORPTION ISOTHERM OF PALMITIC ACID

摘要

The capillary activity of palmitic acid at a stationary mercury electrode was to be investigated by constructing the adsorption isotherm by means of double layer capacity measurements at various potentials. Such data would permit later interpretation of capacitance measurements for a mono¬layer of oriented organic molecules. The influence of double layer structure, which is a function of supporting electrolyte concentration, was also to be studied. The double layer is composed of both an inner and a diffuse region, for each of which a unique capacitance may be defined. It is the present hypothesis that these two capacitances must be distinguished in calculating adsorption isotherms.nThe double layer capacity and surface charge density as a function of potential and concentration were determined for mercury in contact with aqueous NaClO4 as the supporting electrolyte. Sodium perchlorate is adsorbed on the electrode surface at potentials anodic to the electrocapillary maximum by being "squeezed" out of solution. A method based on kinetic and thermodynamic theories of the double layer was devised for calculating the quantities and distributions of charged species present in case the potential of the electro-capillary maximum is lacking.