PITZER MODEL PARAMETERS FOR SPARINGLY SOLUBLE SALTS FROM SOLUBILITY MEASUREMENTS - THALLIUM(I) CHLORIDE IN AQUEOUS-SOLUTIONS OF AMMONIUM-CHLORIDE, RUBIDIUM CHLORIDE AND CESIUM-CHLORIDE AT 298.15-K

Measurements are reported of the solubility of thallium(i) chloride in aqueous solutions of ammonium chloride, rubidium chloride and caesium chloride at 298.15 K at concentrations of added salt up to 4.0 mol kg -1. Pitzer model parameters for TlCl, beta(0) and beta(1), were evalua ted assuming C(phi) = 0. These parameters can account satisfactorily f or the ionic interactions between Tl+ and Cl- without the need to assu me ion association explicitly, thus simplifying the interpretation of the experimental data. Although the parameter alpha = 2, which is cust omarily used for a broad class of electrolytes, is found to be satisfa ctory for TlCl, larger values of alpha generally gave better fits to t he experimental data. Mixture parameters, theta and psi, relevant to t he various mixed electrolytes are also reported.