THE PARTIAL MOLAL VOLUMES OF IONS IN AQUEOUS SOLUTION: I. DEPENDENCE ON CHARGE AND RADIUS

Abstract

The density data for aqueous solutions of electrolytes have been analyzed, and partial molal volumes at infinite dilution have been calculated. The values are shown to be additive, and a set of volumes for individual ions has been prepared, based arbitrarily on a value of zero for the hydrogen ion. It is shown that for a given value of the charge the volumes vary linearly with the cube of the ionic crystal radii, and for a given radius vary with the first power of the charge. In the case of cations the equation obeyed is[Formula: see text]while for anions[Formula: see text]If the volume of the hydrogen ion is taken as −6 ml. instead of zero the same equation is obeyed for both cations and anions, namely[Formula: see text]The empirical equations are discussed in terms of a simple model for ions in solution.