Ternary Diffusion in the Aqueous Solutions of MgCl2 + KCl, CdCl2 + KCl, ZnCl2 + KCl and Onsager's Reciprocity Relations

Abstract

AbstractThe diffusion coefficients D11, D12, D21, and D22 of the three systems MgCl2(1) + KCl(2) + H2O(3), CdCl2(1) + KCl(2) + H2O(3), and ZnCl2(1) + KCl(2) + H2O(3) have been measured at 25°C. The diaphragm cell method was applied. Diffusion coefficients for the following concentrations were obtained c1 = c2 = 0.25, 0.5, 0.75 M, and c1 = 0.25, 0.5, 0.75 M, c2 = 2c1 = 0.5, 1.0, 1.5 M. The Dij values which refer to the cell fixed system were transformed to the D'ij referring to the solvent fixed coordinate system. By the aid of thermodynamic data taken from the literature and from measurements with cells involving the solutions studied the derivatives of the partial chemical potentials δμi/δcj were determined. From all these data the phenomenological coefficients Ω'ij were calculated and we found the result that for MgCl2 + KCl + H2O Ω'12 = Ω'21 is valid whereas for the complex forming systems CdCl2 + KCl and ZnCl2 + KCl our study yielded phenomenological coefficients Ω'12 ≠ Ω'21.