Equations of State for NaCl and CaCl2 Solutions of Arbitrary Concentration at Temperatures 423.15–623.15 K and Pressures up to 5 kbar

Abstract

Equations of state valid for all possible salt concentrations in solution are obtained for binary fluids H₂O—NaCl and H₂O—CaCl₂. The equations are based on the empirical form of the Gibbs free energy for salt solutions of arbitrary concentration, developed earlier. Based on experimental data on the PVTx properties the obtained earlier thermodynamic description of H₂O—NaCl and H₂O—CaCl₂ solutions at saturated vapor pressure is extended towards higher pressures. For H₂O—NaCl pressures are up to 5 kbar. For H₂O—CaCl₂ pressures cover the range of available experimental data up to 0.7 kbar. The equations allow precise calculation of the whole set of thermodynamic parameters of the discussed salt solutions in the temperature ranges 423.15–573.15 K and 423.15–623.15 K, corresponding to low temperature hydrothermal ore deposits, that could be relevant for thermodynamic modeling of ore-bearing fluids at such deposits.