Thermodynamics on the Vapor Formation of Lead Oxychloride

摘要

The vapor pressure of PbCl_2 at high oxygen partial pressure was measured by transpiration method at 923K, 973K and 1023K. The vapor pressure of PbCl_2 decreases with increasing the oxygen partial pressure. The oxygen content in PbCl_2 melt and the chlorine partial pressure in the system increase with increasing the oxygen partial pressure. These results indicate that the activities of PbCl_2 are changed by the formation of lead oxychloride in the melt at high oxygen partial pressure. The formation reaction of lead oxychloride in the- melt is suggested by the reaction PbCl_2 (1) + 1/2O_2 (g) = PbOCl (1) + 1/2Cl_2 (g). Based on the oxygen contents in the PbCl_2 melt and the vapor pressure of PbCl_2, the activities of PbCl_2 and PbO in the PbCl_2-PbO system are calculated. The calculated activities show a negative deviation from Raoult's law.