THERMODYNAMICS OF HIGH-TEMPERATURE ELECTROLYTE-SOLUTIONS - VAPOR-LIQUID-EQUILIBRIUM

Two procedures have been employed to calculate from experimental data the value at infinite dilution of the distribution ratio of electrolyte between the liquid and vapour phases in equilibrium, K(D)infinity. For aqueous NaCl and KCl, K(D)infinity shows the expected asymptotic behaviour when the critical point of the solvent is approached. The thermodynamic evidence suggests that in the range 573 to 643 K the values of K(D)infinity are dominated by a single species. The results were compared to the predictions of cluster theory. Theory indicates that ions in the vapour phase are strongly associated into neutral clusters, the dominant species changing with temperature. In this first report of our work we discuss various alternatives to resolve this apparent discrepancy.