Mole Fraction Of Salt Research Articles

Correlation of the solvation properties of water and dimethyl sulphoxide in metal nitrate–water and metal nitrate–dimethyl sulphoxide melts with the molecular properties of the constituents of the melts

The currently available thermodynamic data obtained by vapour pressure measurements on highly concentrated solutions of single-metal nitrates in water and in dimethyl sulphoxide are numerous and reliable enough to allow us to establish a correlation between the standard solvation free energy, ΔG°sv, of water and dimethyl sulphoxide in (undercooled) liquid nitrates and some of the molecular and ionic parameters which characterize the two molecules and the ionic constituents of the salts. To supplement the previously investigated systems, the system AgNO3–DMSO has been studied by vapour pressure measurements on a dew-point apparatus over the temperature range 330 < T/K < 375 with the salt mole fraction, x, ranging between 0.15 and 0.40. The widely used Stokes–Robinson adsorption–hydration theory has been employed to treat the experimental results and to calculate the values of ΔG°sv. Reasonable linear correlations have been found between ΔG°sv and a function relating the electrostatic cation–dipole interaction energy with physical parameters (charge numbers, ion–dipole distances), suggesting that solvation of both water and dimethyl sulphoxide in liquid nitrates is governed mainly by the cation–dipole electrostatic interaction energy. The roles of the dipole moments and of the donating abilities of the two molecules are pointed out and some suggestions are made concerning the contribution of other energetic and entropic factors to the solvation processes.

Pressions de vapeur des mélanges eau – nitrate d'éthylammonium à 298,15 K. Propriétés thermodynamiques des milieux eau – sel fondu

The activity and activity coefficient of water in water and ethylammonium nitrate (EAN) mixtures were determined by vapor pressure measurements between pure water and pure fused salt at 298.15 K. For a wide range of mole fractions of salt, (0.3 &lt; X ≤ 1) the behaviour of water can be described very accurately by a "one parameter" empirical equation which involves activity coefficient, γE, mole fraction of EAN, and limiting Gibbs energy of the dilution of water in pure fused salt, [Formula: see text]:[Formula: see text]Interpretation of experimental results was also attempted by use of the B.E.T. equation. It appears that the energy, ΔEd = E − EL, in those solutions is very low. Partial molar volumes of water and salt are also discussed in relation to empirical and B.E.T. equations. It can be shown that the two equations lead to similar results.

The density and viscosity of concentrated solutions of silver nitrate in dimethyl sulphoxide

Densities and viscosities of silver nitrate-dimethyl sulphoxide solutions have been measured at 5, 25, and 60 °C over the range of salt mole fractions from 0.05 to 0.5. The dependence of viscosity on the salt concentration has been expressed by an empirical equation and compared with analogous dependences obtained for aqueous solutions of silver nitrate and solutions of other salts in dimethyl sulphoxide.

The density and the molar volumes of the system Ca(NO3)2-KNO3-H2O

The temperature and concentration dependence of the density of the system Ca(NO3)2-KNO3-H2O was studied over a temperature range from -20 to +75 °C and for concentrations given by ionic fractions of the potassium salt of 0.1, 0.2, 0.3, 0.4, and 0.5. The mole fraction of salts ranged from 0.052 to 0.27. The temperature and concentration dependence of calculated molar volumes has been correlated with an empirical equation, assuming additivity of the molar volumes of the salts. Deviations from the additivity principle are discussed and their quantitative description is proposed.

Temperature and concentration dependence of equivalent conductivity in Ca(NO3)2-CaI2-H2O system

The dependence of the equivalent conductivity on the temperature and composition of the Ca(NO3)2-CaI2-H2O system was studied. The ionic fraction [I-]/([I-] + [NO-3]) was changed from 0.1 to 0.5, the mole fraction of calcium salts (assumed in anhydrous form in the presence of free water molecules) was 0.075-0.200. The equivalent conductivity was found to be a linear function of the ionic fraction at constant temperature and salt concentration.

Density, partial molal volume, refractive index, polarizability, and viscosity of concentrated and saturated aqueous solutions of Rochelle salt

The density, refractive index, and viscosity of aqueous solutions of Rochelle salt were measured as a function of its concentration up to saturation at 25OC. Tha apparent partial molal volume and polarizability of the solute obtained from the densities and refractive indices were nearly equal to the molar volume and polarizability of crystalline Rochelle salt. The logarithm of the viscosity was linearly changed against the mole fraction of crystalline Rochelle salt In the aqueous solution up to saturation. The density of the saturated solution was measured as a function of temperature between 10' and 6OoC, and the apparent partial molal volume of the solute in the saturated solution was obtained in the above temperature range. The volume was smaller than the molar volume of crystalline Rochelle salt below about 26OC and slightly larger above the temperature. The activation energies obtained from viscosity were, respectively, 3.78 and 5.02 kcal/mol in 1.0 and 2.5 M solution in the temperature range between 20' and 40'C.

The system sulfur monochloride-tetraethylammonium chloride

The phase diagram for the system sulfur monochloride-tetraethylammonium chloride has been worked out for salt mole fractions (N) from zero to ∼0·5, thermal analysis and other techniques being used. An interesting feature of the system is the occurrence of two immiscible liquid phases between about N = 0·01 and N = 0·17 (at 25°). A pressure-composition study of the same system was also made from N = 0·23 to N = 0·95. No evidence of salt-solvent adduct formation was found in the case of either study.

Bismuth electrodeposition in molten salts

The electrodeposition of bismuth from BiCl 3, Bi 2O 3 and BiOCl dissolved in chloride eutectics and borax melts has been studied. The cathodic deposition of the metal from the fused mixture KCl-LiCl-BiCl 3, at 400–600°C, and low mole fractions of BiCl 3, has been determined by a diffusion process. At higher values of the mole fraction, the discharge of ions at the cathode proceeds without polarization. The cathodic current efficiency increases with the mole fraction of the bismuth salt when temperature and cd are kept constant. In molten CaCl 2-NaCl, Bi 2O 3 appears to be slightly soluble, at 600 to 900°C. The polarization curve of a Mo electrode shows concentration polarization; the limiting cd increases with the temperature. The current efficiency is negligible at 600°C but increases considerably at higher temperature. Concentration polarization is also found in the cathodic deposition of bismuth from a BiOClBaCl 2CaCl 2-NaCl mixture at 900°C. Here, the variation of cathode current efficiency as a function of cd shows a maximum. Polarograms obtained with Mo electrodes for dilute solutions of Bi 2O 3 in molten borax, at 800–1000°C, have wave heights proportional to the concentration. At higher mole fraction the diffusion wave tends to disappear. The dependence of the current efficiency upon cd goes through a maximum at 800°C. Using Pt electrodes, polarograms can be obtained only at 800 and 900°C and 0·01 mole fraction. At larger oxide content and higher temperature there is no concentration polarization. In the same way, polarization curves with Bi electrodes show no controlling diffusion process at any mole fraction and temperature.