THE DENSITY MODEL FOR ESTIMATION OF THERMODYNAMIC PARAMETERS OF REACTIONS AT HIGH-TEMPERATURES AND PRESSURES

Equations are presented for the calculation of the equilibrium constant and standard state thermodynamic properties at high temperatures and pressures of reactions involving both aqueous species and minerals, given a knowledge of the equilibrium constant and the standard enthalpy and heat capacity of the reactions at reference conditions. The equations are based on a model variation of the heat capacity of reaction which uses reference state values and solvent properties only, notably the temperature derivative of the coefficient of thermal expansion of water.