Critical Evaluation of the Thermodynamic Properties of Aqueous Calcium Chloride. 1. Osmotic and Activity Coefficients of 0−10.77 mol·kg-1 Aqueous Calcium Chloride Solutions at 298.15 K and Correlation with Extended Pitzer Ion-Interaction Models

摘要: Isopiestic vapor-pressure measurements were performed at 298.15 K for CaCl2(aq) solutions 66 molalities from (4.3235 to 10.253) mol·kg-1, using H2SO4(aq) as the reference standard, with emphasis given accurate characterization of osmotic coefficients near and above saturation. Published isopiestic molalities, direct vapor pressures, emf results have been critically reevaluated recalculated in an internally consistent manner. This critically-assessed database was used evaluate parameters Pitzer's equations various extended forms 0.1 MPa. Neither standard nor empirically versions able represent thermodynamic over more than part molality range without large cyclic systematic deviations. It possible, however, obtain essentially quantitative agreement between experiment model full if (1) presence CaCl+(aq) ion pairs included explicitly (2) higher-...