Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Correlation algorithms for ionic species and equation of state predictions to 5 kb and 1000°C

Abstract

Correlation algorithms permit prediction of species-dependent parameters in revised equations of state (tanger and Helgeson, 1988) for aqueous ions and electrolytes which can be used together with values at 25°C and 1 bar of the standard partial molal entropies (S0), volumes (V0), and heat capacities (C0p) of the ions to calculate their standard partial molal thermodynamic properties at pressures and temperatures to 5 kb and 1000°C. Values of V0 and C0p at 25°C and 1 bar have been calculated for 128 aqueous ions from analysis of published experimental data or from correlations of these properties with S0. Equation of state parameters have also been generated for these ions and examples are given of predicted standard partial molal thermodynamic properties of representative cations and anions at high pressures and temperatures. Close agreement between independently predicted and experimentally determined equilibrium constants for acid anion dissociation reactions at high temperatures supports the validity and generality of the predictive algorithms.