Measurements of self-diffusion coefficients of water in pure water and in aqueous electrolyte solutions

Self-diffusion coefficients of water in pure water and in aqueous solutions of several electrolytes at various temperatures have been measured using the diaphragm cell method with deuterium as tracer. Electrolytes investigated were ammonium chloride, ammonium sulphate, potassium nitrate, potassium chloride, sodium chloride and lithium chloride. Dissolved ammonium chloride and potassium chloride have practically no effect on the diffusion of water molecules. Potassium nitrate tends to increase the diffusion rate of water, while the other electrolytes reduce the diffusion rate with increasing concentrations. From the temperature dependence of the self-diffusion coefficients of water in electrolyte solutions the activation energies have been determined. The results are discussed by considering the effect of hydration.