Vapor Pressure of Bismuth

Abstract

The total vapor pressure of bismuth as determined in the temperature range 1196°—1268°K by the quasistatic and boiling‐point methods is represented by logp(torr) = − (9150.3/T)+7.6327. The bismuth vapor density as found by the transpiration method is 3.05×10⁻³ g/liter at 1173°K. A combination of the pressure and density data yields an average molecular weight of the vapor at 1173°K of 328 which implies 57 mole % Bi₂ and 43 mole % Bi in the vapor, and partial pressures of 0.29 and 0.39 torr for the monatomic and diatomic species, respectively. The standard enthalpies of dissociation of Bi₂(g) and of vaporization of liquid to monatomic and diatomic species are 47.8, 50.3, and 52.8 kcal/mole, respectively. The results are compared with those of other workers.