THE ELECTRICAL DOUBLE-LAYER AT THE INTERFACE BETWEEN MERCURY AND A POLYETHER ELECTROLYTE .2. THE EFFECT OF VARYING THE RELATIVE MOLAR-MASS OF THE SOLVENT

Differential capacitance measurements made at a hanging mercury drop electrode using highly purified solvents are compared for a series of LiAsF6 solutions in CH3O(CH2CH2O)(n)CH3 for n=1, 2, 4, 8 and 10. Measured values of the capacitance were essentially independent of the relative molar mass of the solvent except for n=1 where the values in the cathodic region were lower and close to those reported for tetrahydrofuran. The inner-layer capacitance was determined as a function of charge density for n=10 and, using Parsons' four-state model, was shown to behave similarly to ''group 1/group 2'' solvents. By subtracting the contribution of the metal to the inner-layer capacitance, it is shown that there is no significant preferential orientation of the dipoles at the potential of zero charge at the mercury surface for LiAsF6 solutions for n=10.