Vapour phase composition and activities for the molten PbBr₂+KBr system

Abstract

Vapour pressures above molten PbBr₂+KBr mixtures have been measured over a range of temperatures by a transpiration method. The vapours have been investigated also by mass spectrometry and the presence of the complex KPbBr₃ has been established. The enthalpy and entropy of formation of this compound from PbBr₂(g) and KBr(g) are similar to values obtained for the analogous chloride species. By combining the results of both methods, the true activities of lead bromide in the melt have been calculated as a function of composition, and the results have been interpreted to show that PbBr₃ is the major complex ion present in the molten mixtures.