Solvent structure. II. A study of the structure-making and structure-breaking effects of dissolved species in water by internal pressure measurements

Abstract

Internal pressures, (∂U/∂V)_T, have been obtained at 25ºC for solutions of 25 solutes in water by measurement of the thermal pressure coefficients. Values at 1.00 M solute concentration were plotted against the molar volume of the solutes. Those solutes (electrolytes) which appear above a line joining five solutes acting as 'non-interacting' homomorphs were judged to be structure breakers in water; those solutes (lithium salts, tetraalkylammonium salts, non-electrolytes) appearing below the line were termed structure makers. These observations are in agreement with current knowledge, and they substantiate the present interpretation of the physical significance of internal pressures.