Thermodynamics of Electrolyte Mixtures: HCl + NdCl3 + H2O from 5 to 55 ∘C

Abstract

Electromotive-force (emf) measurements of cells containing solutions of hydrochloric acid and neodymium chloride were reported at constant total ionic strengths (I) of 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, and 1.5 mol-kg−1 at 11 temperatures ranging from 5 to 55 ∘C, and at I = 2.0 mol-kg−1 at 25 ∘C. Hydrogen and silver–silver chloride electrodes were used in these cells. Results from the emf measurements, the mean molal activity coefficients of HCl in HCl + NdCl3 + H2O mixtures, as well as the Harned interaction coefficients using Harned's rule are reported in the preceding article in this issue. The ion-interaction model of Pitzer is applied here for the evaluation of the Pitzer mixing coefficients, SθH,Nd and ψH,Cl,Nd, as well as the linear representation of the temperature derivatives of ∂SθH,Nd /∂ T and ∂ψH,Nd,Cl/∂T. The activity coefficients at several ionic strength fractions y of NdCl3 are given at 25 ∘C. The results are interpreted in terms of ionic interactions.