Activity coefficients of NaCl in NaCl–NaOAc–H2O at 25, 35, and 45 °C

The activity coefficients of NaCl were estimated by measuring the EMFs of the cell[Formula: see text]at four ionic strengths, i.e., 0.5, 1.0, 2.0, and 3.0 mol/kg and at temperatures 25, 35, and 45 °C. The results were analyzed in terms of Harned's rule, the Pitzer and Rush–Johnson–Scatchard treatments. Osmotic coefficients and excess free energies of mixing were calculated at all ionic strengths and temperatures studied. Key words: activity coefficients, sodium chloride, sodium acetate, Pitzer formalism, Scatchard equation.

Thermodynamic properties of multicomponent electrolyte solutions in mixed solvents. 5• HCl + NaCl + urea + water at 278.5–318.15 K

This paper reports electromotive force measurements of the cells[Formula: see text]and[Formula: see text]in mixed solvents of urea, mole fraction x = 0.05, at five temperatures from 278.15 to 318.15 K. The standard potentials of Ag–AgCl electrode in mixed solvents were obtained from the emf of cell (A) for HCl of molality mA from 0.02 to 0.11 mol kg−1, both by extrapolation on the basis of an extended Debye–Hückel equation and by a polynomial approach proposed in this paper on the basis of Pitzer's electrolytic solution theory. The standard free energies of transfer for HCl are discussed. The activity coefficients of HClγA in HCl + NaCl + urea + water have also been obtained from the emf of cell (B) at constant total ionic strength I = 0.5, 1.0, 1.5, and 2.0 mol kg−1. The experimental results show that HCl obeys Harned's rule and log γA is a linear function of absolute temperature T. They also indicate that the relative partial molar enthalpy of HCl obeys a similar Harned's rule.

Thermodynamics of Mixed Electrolyte Solutions

A general thermodynamic expression has been derived for the deviation Δ from Zdanovskii's rule. Conditions have been deduced under which Δ vanishes, and examples given. For nonzero values of Δ it has been shown by means of an example that Δ may be evaluated in some cases by the introduction of empirical assumptions, such as Harned's rule. The use of Zdanovskii's rule in facilitating the integration of the McKay–Perring equation has been discussed briefly.