Adiabatic Compressibilities of Some Aqueous Ionic Solutions and Their Variation with Indicated Liquid Structure of the Water

Abstract

The adiabatic compressibilities of aqueous solutions of twenty-seven strong electrolytes, each at a single concentration, were determined at 25°C from sound velocity measurements at a supersonic frequency (1015.24 kc/sec.). The change in compressibility per mole fraction of solute shows a satisfactory correlation with x-ray and other indications of water structure change. Adiabatic compressibility values themselves show a remarkable correlation with corresponding values of the partial molal volume of the solvent water. Evidence strongly supports the conclusion that water has a liquid structure which becomes more highly coordinated and compacted with the introduction of ions.