I.A. Uspenskaya

Phase equilibria in water-propanol(−1, −2) systems

The literature data on the thermodynamic properties of and phase equilibria in the water-1-(2-)C3H7OH systems were considered. The nonrandom two-liquids model was used to optimize the data on liquid-vapor equilibria in these systems, estimate model parameters and errors in them, and calculate and construct the corresponding phase diagrams. The results were compared with the data published earlier.

The thermodynamic properties of solutions of sodium chloride, water, and 1-propanol

The temperature-concentration dependences of the activity coefficient of NaCl in aqueous solutions of 1-propanol at 298 and 318 K, solution ionic strength up to 3m, and alcohol contents of 10–40 wt % were determined by the method of electromotive forces with ion-selective electrodes. The results were used to estimate interaction parameters in the Pitzer model. The Darken method was used to calculate the integral Gibbs energy of solutions.

Thermodynamic assessment of the copper-gadolinium system

The literature data on the thermodynamic properties and phase equilibria in the copper-gadolinium system were generalized. A set of thermodynamic model parameters for system phases that best described these data were obtained. The phase diagram of the system over the temperature range 300–2000 K at a pressure of 1 bar was calculated.

Crystal structures and physicochemical properties of mixed salts of ammonium nitrate and sulfate

Mixed salts (NH4)2SO4·2NH4NO3 (1) and (NH4)2SO4·3NH4NO3 (2) were synthesized and studied by X-ray diffraction analysis. The unit cell parameters of these salts were determined and their crystal structures were solved. The thermal stability of the salts was studied by differential scanning calorimetry and thermogravimetric analysis. The temperatures and enthalpies of incongruent melting of compounds 1 and 2 were determined. The enthalpies of formation from the constituent salts were estimated.

Thermodynamic properties of aqueous-alcoholic solutions of sodium chloride. H2O-2-C3H7OH-NaCl

The temperature-concentration dependences of the NaCl activity coefficient in aqueous solutions of isopropanol (propanol-2) at temperatures of 298.15 and 323.15 K (solution ionic force, 0.01 to 3m; alcohol content, 10–60 wt %) were determined through the electromotive force method with an ion-selective electrode. A Pitzer model was used to mathematically describe the thermodynamic properties. The integral Gibbs energy of the solution formation of the H2O-2-C3H7OH-NaCl ternary system was performed according to Darken’s method. The dissociation degree of salt in the investigated solutions was estimated using the literature data on the association constant of NaCl in aqueous-isopropanol solution.

The thermodynamic properties of Ln2BaO4 (Ln = Sm, Dy, Ho)

The thermodynamic properties of the Ln2BaO4 phases (Ln = Dy, Ho, Sm) were studied by the electromotive force method with a fluoride electrolyte (890–1180 K), solution calorimetry in 1.07 N hydrochloric acid at 298.15 K, and differential scanning calorimetry (298–860 K). The experimental data were jointly processed, and the thermodynamic functions of the compounds over the temperature range 298–1200 K were calculated.

Thermodynamic properties of solutions in the system o-xylene–di-2(ethylhexyl)phosphoric acid

The saturated vapor pressure in the temperature range of 298.15–308.15 K and the density of solutions in the o-xylene–di-2(ethylhexyl)phosphoric acid system at 298.15 K are measured. The activity coefficients of o-xylene in the above temperature range are calculated on the basis of the resulting data. The parameters of the thermodynamic model UNIQUAC are determined and analytical relationships are proposed to describe the bulk properties of the solution.

Thermodynamic modeling of redox equilibria in sodium silicate glasses with low iron content

The available literature data on the content of oxidized and reduced iron forms in molten sodium silicates at temperatures the 1573–1873 K and partial oxygen pressures 10−8−0.21 bar have been scrutinized. On the basis of this information, the temperature dependence of the Fe2O3 activity coefficient in glass melts containing up to 4 mol % Fe (“Henrian” solution) has been suggested in the framework of the quasi-chemical model. The results are compared with previous data.

Volumetric Properties of Binary and Ternary Solutions in the Water–Urea–Ammonium Sulfamate System

Densities of liquid phases in the water–urea–ammonium sulfamate ternary system and in the binary water–ammonium sulfamate subsystem were investigated in a wide concentration range at 288.15, 298.15 and 323.15 K. A volumetric model of the aqueous ternary solutions was proposed.

Phase equilibria in water-(1-, 2-, iso-)butanol-18-crown-6 systems

We present the results from measuring the solubility of 18-crown-6 in isobutanol in the temperature interval of 280–308 K and information about liquid-liquid equilibria in water-(1-, 2-, iso-)butanol-18-crown-6 systems at 298 K. The parameter values of the extended UNIQUAC model were determined on the basis of information about the thermodynamic properties and phase equilibria in the binary systems. It is shown that we must use parameters of ternary interaction in addition to binary parameters to adequately describe the miscibility gap on the basis of the results of turbidimetric titration in ternary water-(1-,2-, iso)butanol-18-crown-6 systems.