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: $$\begin{array}{c}\mathrm{Reaction}{\mathrm{\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\Delta H}}_0^o\hspace{0.17em}\mathrm{kcal}/\mathrm{mole}\\ \mathrm{MoO}(\mathrm{g}\mathrm{)\to }\mathrm{Mo}(\mathrm{g}\mathrm{)+}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}116±15}\\ {\mathrm{MoO}}_2(\mathrm{g}\mathrm{)\to }\mathrm{Mo}(\mathrm{g}\text{)+2}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}262±10}\\ {\mathrm{MoO}}_3(\mathrm{g}\mathrm{)\to }\mathrm{Mo}(\mathrm{g}\text{)+3}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}411±7}\\ \mathrm{WO}(\mathrm{g}\mathrm{)\to }\mathrm{W}(\mathrm{g}\mathrm{)+}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}154±10}\\ {\mathrm{WO}}_2(\mathrm{g}\mathrm{)\to }\mathrm{W}(\mathrm{g}\text{)+2}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}296±7}\\ {\mathrm{WO}}_3(\mathrm{g}\mathrm{)\to }\mathrm{W}(\mathrm{g}\text{)+3}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}443±7}\\ \mathrm{UO}(\mathrm{g}\mathrm{)\to }\mathrm{U}(\mathrm{g}\mathrm{)+}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}179±7}\\ {\mathrm{UO}}_2(\mathrm{g}\mathrm{)\to }\mathrm{U}(\mathrm{g}\text{)+2}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}340±7}\\ {\mathrm{UO}}_3(\mathrm{g}\mathrm{)\to }\mathrm{U}(\mathrm{g}\text{)+3}\mathrm{O}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}493±7}\\ \mathrm{U}(\mathrm{s}\mathrm{)\to }\mathrm{U}(\mathrm{g}\text{)\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}\hspace{0.17em}126±5.}\end{array}$$