Abstract
Measured values of the pressure of H2O over saturated solutions in equilibrium with the dihydrate, tetrahydrate or hexahydrate of CaCl2 are converted to osmotic coefficients and compared with literature values for solutions of smaller molality. It is found that the osmotic coefficient is constant, within the uncertainty, from about 7 mol-kg−1 to soturation at all temperatures from 25 to 100°C. From this simple approximation, the activity coefficient is calculated for high molalities and at saturation. By combination of these results with other established data, entropies and Gibbs energies of formation are calculated for the crystalline hydrates of CaCl2.
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Pitzer, K.S., Shi, Y. Thermodynamics of calcium chloride in highly concentrated aqueous solution and in hydrated crystals. J Solution Chem 22, 99–105 (1993). https://doi.org/10.1007/BF00650677
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DOI: https://doi.org/10.1007/BF00650677