Vapor pressure measurement of zinc oxychloride

The vapor pressures of ZnCl2 at high oxygen partial pressure were measured by transpiration method at 823 K and 873 K. The vapor pressures of ZnCl2 decreased with increase of the oxygen partial pressure. The oxygen content in ZnCl2 melt and the chlorine partial pressure in the system increased with increasing the oxygen partial pressure. These results indicate that the activities of ZnCl2 melt are changed by the formation of zinc oxychloride in the melt at high oxygen partial pressure. The formation reaction of zinc oxychloride in the melt is suggested by the reaction ZnCl2 (l) + 1/2 O-2 (g) =ZnOCl (l) + 1/2 Cl-2 (g). From the oxygen contents in the ZnCl2 melt and the vapor pressure of ZnCl2, the activities of ZnCl2 in the ZnCl2-ZnO system are calculated. The activities of ZnCl2 in the system show a negative deviation from Raoult's law.