Unusual ion solvation energies in high temperature water

Abstract

Classical hydration theory predicts a decreasing temperature stability for ions in aqueous solutions while the energy of ion-solvent interaction increases. Born theory has been modified to take into account a non-electrostatic entropy term which accounts for loss of degrees of freedom of solvating molecules, and a change in standard state volume. Such a theory predicts very large solvation energies (>10⁵ cal mol^–1 at 300°C); this new phenomenon has been verified by measurement of the heats of solution of ionic salts at 300°C in a pressurized calorimeter.