Viscosity of solutions of NaI and CaCl2 in water–ethanol and of Nai in water–tetrahydrofuran mixtures

Abstract

Viscosity measurements of solutions of NaI and CaCl₂ in water–ethanol mixtures and of NaI solutions in water–tetrahydrofuran mixtures have been performed at 20, 25 and 30 °C. The salt concentration was 0.05 mol kg^–1 of solvent. Minima in the relative viscosity corresponding to ca. 12 mol% ethanol and 2.5 mol% THF have been observed. The temperature coefficients of the relative viscosities have been calculated and interpreted from the viewpoint of the effect of the investigated electrolytes on the water–organic solvent mixtures. The dependence of η_r=f(organic solvent content) has been compared with the analogous relationship for the standard enthalpy of solution of the investigated salt. The correlation between η_r(or B)=f(ΔH°_s) has been found to be linear over a wide region of mixed solvent compositions, not only in the mixtures of water with ethanol and THF but in other water–organic solvent systems.