Mass Transport in Aqueous Zinc Chloride‐Potassium Chloride Electrolytes

Conductimetric and diaphragm cell techniques have been used to measure ternary diffusion coefficients for aqueous zinc chloride‐potassium chloride solutions at 25°C. At low concentrations where Zn 2+ is the major zinc‐transporting species, the diffusion‐induced electric field along zinc chloride concentration gradients drives large co‐current flows of potassium chloride. In concentrated solutions where a large proportion of zinc diffuses as anionic ZnCl − 3 and ZnCl 2‐ 4 complexes, flow of zinc chloride generates counterflow of potassium chloride. If a sharp zinc chloride gradient is formed in an otherwise uniform solution of potassium chloride, coupled diffusion can concentrate potassium ions within the diffusion boundary. Equations are developed to predict multicomponent transport coefficients for zinc chloride in supporting electrolytes.