Thermodynamic consistency of solubility and vapor pressure of a binary saturated salt + water system: II. CaCl2 + H2O

Solubility data of CaCl2·nH2O (n = 2, 4, 6) were predicted and evaluated by a Stokes and Robinsonʹs adjusted BET-model using the vapor pressures of saturated solution as criteria. Prior to the prediction, the BET model was parameterized with the most recently reported experimental osmotic coefficients. The comparison with other models showed that, despite of fewer model parameters, the BET model could represent the activities in the system CaCl2 + H2O as good as the Pitzer model in a large temperature range from 298.15 to 523.15 K. Meanwhile, experimental vapor pressure data of the saturated CaCl2 solution were critically evaluated and some of them are selected as criteria for solubility prediction. In principle, the predicted solubility has higher accuracy than an average set of various experimental data and therefore is recommended for use in relevant cases.