The Entropy of Dilution of Strong Electrolytes in Aqueous Solutions

Abstract

The relative partial molal entropy of water, S̄1–S10, in aqueous electrolyte solutions is calculated from existing data. An attempt is made to correlate these values with changes in the structure of water in the solutions. It is found that cations of small radii and ions capable of forming hydrogen bonds with the water, such as H3O+, OH— and NH+4, help to stabilize the water structure, while large ions and ions of nonspherical and nontetrahedral shapes have an effect in the opposite direction. In dilute solutions the entropy of dilution depends largely on the ionic strength. In all cases deviations from the Debye-Hückel limiting law are positive.