The properties of the electrical double layer III: The capacity of the double layer on Hg and on AgI

Abstract

Abstract A model of the double layer on the basis of the Gouy‐Stern theory is given assuming the absence of chemisorption of counterions. The capacity K of the Stern layer is taken to be constant, but the χ potential located in the first water layer at the phase boundary is assumed to be a function of the surface charge. This theory is discussed using as an example the capacities of the Hg electrode in NaF solutions. The adsorption of silver and iodide ions on AgI at different concentrations of NaClO 4 in water, 25% vol. and 100% vol. acetone were determined. The capacities of the double layer on AgI calculated from these adsorption curves are in many respects similar to the usual capacity curves of Hg. There are, however, some qualitative differences. The theory of Grimley and Mott about the double diffuse layer is discussed. Comparison with experiment shows the influence of the diffuse layer in solid AgI on the total capacity to be small.