Pitzer's parameters for thallium(I) chloride in aqueous solutions at 298.15 K from solubility measurements in TlCl–LiCl–H2O and TlCl–KCl–H2O systems

Abstract

The solubility of thallium(I) chloride has been measured in aqueous solutions of lithium chloride and potassium chloride at concentrations ranging from 0.005 to 4.0 mol kg^–1 at 298.15 K. The data were analysed using Pitzer's virial coefficient treatment without explicit assumption of association to ion pairs. Single electrolyte parameters for TICl, β^(o) and β⁽¹⁾ were evaluated assuming C^ϕ= 0. Although α= 2 gave a satisfactory fit of the experimental data, as it does for a wide variety of electrolytes, the best fit of the experimental data was obtained with α= 7. However, when the results were combined with those for previous systems, it was found that α= 2 gave more consistent values for Pitzer's parameters as well as the thermodynamic solubility product of thallium(I) chloride. Mixture parameters relevant to a particular mixture, θ and ψ, were also evaluated.