The viscosity of concentrated electrolyte solutions. II. Temperature dependence

Abstract

The temperature dependence of the viscosity of concentrated aqueous electrolyte solutions has been explained in terms of the temperature dependence of the E and V parameters of an equation previously developed for the viscosity of such solutions. Analysis of the V parameters for the alkali halide and ammonium halide salts leads to absolute ionic hydration numbers. The temperature dependence of these hydration numbers reveals two types of ionic behaviour: structure making ions and structure breaking ions. The Gourary–Adrian scale of ionic radii is found to be more consistent with these data and the temperature dependence than the Pauling ionic radii scale.Analysis of the E parameters leads to the ionic free energy of activation parameters for viscous flow of the ions. The Furth model for hole formation in a liquid is found to correlate these ionic free energy values with the absolute ionic volume parameters obtained from the analysis of the V parameter for all salts. Again the ions are found to break into structure making and structure breaking groups in terms of the surface tension values for the water about the hydrated ions.