A comprehensive data set of thermodynamic and calorimetric properties of calcium nitrate aqueous solutions, including the heats of dilution, heat capacity, and phase equilibria in a wide temperature and concentration range is thoroughly collected and critically reviewed. A temperature-dependent Pitzer− Simonson−Clegg model is proposed to describe reliably the properties of liquid phase as well as solid−liquid (SLE) and vapor− liquid (VLE) equilibria, including metastable ones, over T = (243.15 to 425.75) K and up to x(Ca(NO 3 ) 2 ) = 0.3. Improved accuracy is obtained as compared to that of earlier models along with incorporating many diverse experimental data types simultaneously.

Obtained isothermal sections of the ZnCl 2 −Zn(CH 3 SO 3 ) 2 −H 2 O phase diagram at −10.8 and 25 °C (262.35 and 298.15 K) showed the Zn(CH 3 SO 3 ) 2 •4H 2 O hydrate to be stable under 25 °C in compositions with high ZnCl 2 content. The change of the solubility of the Zn(CH 3 SO 3 ) 2 •4H 2 O is slower with temperature than that of Zn(CH 3 SO 3 ) 2 •12H 2 O both in binary and ternary mixtures. The Laliberte model parameters were obtained for Zn(CH 3 SO 3 ) 2 −H 2 O and were used to predict density in the ternary aqueous solutions. Density and water activity of the aqueous solutions containing both ZnCl 2 and Zn(CH 3 SO 3 ) 2 were measured at several temperatures. The measured values were compared with predicted densities; the deviation does not exceed 2% for all compositions.

A new equation of state is proposed for a solution of gas at infinite dilution, based on considering the interaction between a gas and a solvent at the microscopic level. It is used to describe the properties of an infinitely dilute aqueous solution of argon in a wide range of temperatures and pressures, including the supercritical region of water. It is shown that the resulting equation is capable of predicting the properties of an aqueous solution of an inert gas with high accuracy, based on a limited set of data at moderate temperatures.

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