Mass Spectrometric Study of Gaseous Molybdenum, Tungsten, and Uranium Oxides

Abstract

Partial pressures of the gaseous oxides MoO, MoO2, MoO3, WO, WO2, WO3, UO, UO2, and UO3 in the systems Mo–Al2O3 and U–Al2O3 have been measured by mass spectrometric methods. The vapor pressure of uranium has also been determined. The reaction enthalpies derived from these measurements are: Reaction ΔH0ο kcal/moleMoO(g)→Mo(g)+O(g) 116±15MoO2(g)→Mo(g)+2O(g) 262±10MoO3(g)→Mo(g)+3O(g) 411±7WO(g)→W(g)+O(g) 154±10WO2(g)→W(g)+2O(g) 296±7WO3(g)→W(g)+3O(g) 443±7UO(g)→U(g)+O(g) 179±7UO2(g)→U(g)+2O(g) 340±7UO3(g)→U(g)+3O(g) 493±7U(s)→U(g) 126±5.