Transport properties of 2:2 symmetrical electrolytes in (water + ethylene glycol) binary mixtures at T = 293.15 K

Abstract

The specific conductivities ( k), the densities ( ρ), and the absolute viscosities ( η) of solutions of zinc(II) sulfate in (water + ethylene glycol) (EG) binary mixtures have been measured at T = 293.15 K. The conductivity data have been analyzed using the Lee–Wheaton conductivity equation and the limiting molar conductivities ( Λ o), the association constants ( K A), and the centre-to-centre distance of the formed ion pairs ( α) have been derived. The limiting ion conductivities ( λ ± ∘ ) have been evaluated and used for the calculation of the “corrected” Stoke’s radii ( r Cor), according to the method proposed by Robinson and Stokes. The ion mobilities have been found to be controlled completely by the bulk viscosity. The ionic association was enhanced with the increasing of the EG content in the solvent mixtures, due to the gradual decrease of the dielectric constant of the solvent medium. The formed ion pairs have been recognized to be solvent separated pairs. The viscosity data have been interpreted in terms of the Jones–Dole equation. The B i viscosity coefficient indicated that the Zn 2+ ion acts as a “structure maker”.