A reinvestigation of the enthalpy changes for the interaction of the sulphate ion with some transition-metal ions in aqueous solution

Abstract

Calorimetric enthalpy data are reported for the interaction of the sulphate ion with divalent Mg, Mn, Co, Cu, and Zn ions in aqueous solution. Data are compared with those from other calorimetric and ‘temperature coefficient’ studies. The small dependence of ΔH° on the accuracy of log K° and the significant dependence of ΔH° on the choice of mean activity-coefficient expression are discussed. The chosen activity-coefficient expression contributes significantly to the computed solution compositions and to the correction of enthalpy data to infinite dilution; it is mainly these factors which give rise to the variance between reported calorimetric results.