Summary of the Apparent Standard Partial Molal Gibbs Free Energies of Formation of Aqueous Species, Minerals, and Gases at Pressures 1 to 5000 Bars and Temperatures 25 to 1000 °C

Abstract

Accurate values of the apparent standard partial molal Gibbs free energies of formation (ΔḠ°) of aqueous species, minerals, and gases at high temperatures and pressures are a requisite for characterizing a variety of industrial and natural processes including corrosion of metals, solvent extraction, crystal growth, metamorphism, and the formation of hydrothermal ore deposits. Revision of the HKF equations of state for aqueous species other than H₂O (Helgeson, Kirkham and Flowers, 1981) by Tanger and Helgeson (1988) and Shock et al. (1992) permits calculation of ΔḠ° for these species at temperatures to 1000 °C and pressures to 5000 bars. The revised equations of state were combined with parameters generated by Shock and Helgeson (1988, 1990), Shock and McKinnon (1993), Shock and Koretsky (1993), Schulte and Shock (1993), Pokrovskii and Helgeson (1995 a, b, and c), and Sverjensky et al. (1995) together with densities and electrostatic properties of H₂O computed from equations summarized by Johnson and Norton (1991) to calculate values of ΔḠ° for aqueous species as a function of temperature and pressure. The results of these calculations are tabulated for 348 such species, including both inorganic and organic aqueous ions, neutral species, and metal ligand complexes. Similar calculations using equations, parameters, and thermodynamic data taken from Kelley (1960), Helgeson et al. (1982), Hill (1990), Shock (1993), and Pokrovskii and Helgeson (1995 a and b) were used to generate tables of ΔḠ° for H₂O, 22 minerals, and 18 gases. The tabulated values of ΔḠ°, which were generated with the aid of SUPCRT92 (Johnson et al., 1992), facilitate considerably assessment of the thermodynamic behavior of chemical processes at both high and low temperatures and pressures.