Activities from vapor pressure measurements of lithium and of sodium chlorates in water and water–dioxane solvents

Abstract

The vapor pressures of solutions of sodium chlorate and of lithium chlorate in water and in solvents consisting of 44.5% dioxane–55.5% water and of 64.5% dioxane–35.5% water, at 25 °C, were determined using a differential manometer. The vapor compositions of the dioxane–water solutions were found by the air-saturation method.The mean molal activity coefficients were calculated from the vapor pressures and compositions. The activity coefficients of the solute were fitted to the theoretical equations of Stokes and Robinson and of Glueckauf, yielding hydration numbers for the cations of the salts.The minimum dioxanation numbers of sodium and of lithium chlorates in the dioxane–water mixtures were calculated from the experimental activity coefficients by the method of Grunwald. The results show that lithium chlorate is more highly solvated than sodium chlorate and that dioxane plays a major role in the solvation of both electrolytes in the dioxane–water mixtures.