Measurement and correlation of osmotic coefficients and evaluation of vapor pressures for solutions of CaCl2 and Ca(NO3)2 in ethanol at 298 K

The osmotic coefficients of calcium chloride and calcium nitrate in ethanol have been measured by the isopiestic method at 298 K. Sodium iodide was used as isopiestic standard for the calculation of osmotic coefficients. The molality range covered in this study correspond to about 0.1–2.3 mol kg−1 for CaCl2 and 0.3–3 mol kg−1 for Ca(NO3)2. The system of equations developed by Clegg et al. [S.L. Clegg, K.S. Pitzer, P. Brimblecombe, J. Phys. Chem. 96 (1992) 9470–9479], Chen [C.C. Chen, L.B.A. Evans, AIChE J. 32 (1986) 444–454], Haghtalab–Vera [A. Haghtalab, J.H. Vera, AIChE J. 34 (1988) 803–813] and Pitzer [K.S. Pitzer, G. Mayorga, J. Phys. Chem. 77 (1973) 2300–2308; K.S. Pitzer, Activity Coefficients in Electrolyte Solutions, 2nd Edition, CRC press, Boca Raton, FL, 1991; K.S. Pitzer, J. Am. Chem. Soc. 102 (1980) 2903–2906; K.S. Pitzer, J.M. Simonson, J. Phys. Chem. 90 (1986) 3005–3009] were used to fit each set of osmotic coefficients. The parameters from the fit were used to calculate the vapor pressures. The osmotic coefficient data are successfully correlated with these models, and the models provide reliable predictions of vapor pressures.