ISSN:
0044-2313
Keywords:
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Total Pressure Measurements and Gas Phase Composition over Re2O7, ReO3, and ReO2The total pressures over Re2O7, ReO3, and ReO2 have been determined by means of a membrane pressure gauge. The sublimation pressure over Re2O7 will be measureable at a temperature above 225°C and amounts 230 Torr at the melting point (at 315°C).The values are \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\Delta {\rm H}^ \circ ({\rm sub,}\,{\rm Re}_{\rm 2} {\rm O}_{\rm 7},\,{\rm T)}\,{\rm = }\,{\rm 135}{\rm .1}\, \pm \,{\rm 2}\,{\rm kJ/mol}} \hfill \\ {\Delta {\rm S}^ \circ ({\rm sub,}\,{\rm Re}_{\rm 2} {\rm O}_{\scriptstyle {\rm 7} \hfill \atop \scriptstyle \hfill},\,{\rm T)}\,{\rm = }\,220.{\rm 5}\, \pm \,3.3\,{\rm J/K}\, \cdot {\rm mol}} \hfill \\ \end{array} $$\end{document}.ReO3 decomposes at a temperature above 400°C according to \documentclass{article}\pagestyle{empty}\begin{document}$$ 3\,{\rm ReO}_{\rm 3},\,{\rm f}\,{\rm = }\,{\rm ReO}_{\rm 2},{\rm f}\,{\rm + }\,{\rm Re}_{\rm 2} {\rm O}_{\rm 7},{\rm g} $$\end{document} with ΔH°r,T = 214.6 ± 2kJ/mol and ΔS°r,T = 263.2 ± 4J/K · mol.ReO3 is not detectable in the gaseous phase in measurable quantities. ReO2 decomposes at a temperature above 800°C according to \documentclass{article}\pagestyle{empty}\begin{document}$$ 7/2\,{\mathop{\rm Re}\nolimits} {\rm O}_{\rm 2},{\rm s}\,{\rm = }\,{\rm 3/2}\,{\rm Re, s}\,{\rm + }\,{\rm Re}_{\rm 2} {\rm O}_{\rm 7},{\rm g} $$\end{document} with ΔH°r,T = 387,0 ± 8.4 kJ/mol and ΔS°r,T = 289.1 ± 12.5 J/K · mol.
Notes:
Die Gesamtdrücke über Re2O7, ReO3 und ReO2 wurden im Membrannullmanometer bestimmt. Der Sublimationsdruck über Re2O7 wird oberhalb 225°C meßbar und erreicht am Schmelzpunkt (bei 315°C) 230 Torr.Es sind \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\Delta {\rm H}^ \circ ({\rm sub,}\,{\rm Re}_{\rm 2} {\rm O}_{\rm 7},\,{\rm T)}\,{\rm = }\,{\rm 135,1}\, \pm \,{\rm 2}\,{\rm kJ/mol}} \hfill \\ {\Delta {\rm S}^ \circ ({\rm sub,}\,{\rm Re}_{\rm 2} {\rm O}_{\rm 7},\,{\rm T)}\,{\rm = }\,220{\rm,5}\, \pm \,3,3\,{\rm J/K}\, \cdot {\rm mol}} \hfill \\ \end{array} $$\end{document}.ReO3 zersetzt sich oberhalb 400°C nach \documentclass{article}\pagestyle{empty}\begin{document}$$ 3\,{\rm ReO}_{\rm 3},\,{\rm f}\,{\rm = }\,{\rm ReO}_{\rm 2},{\rm f}\,{\rm + }\,{\rm Re}_{\rm 2} {\rm O}_{\rm 7},{\rm g} $$\end{document} mit δH°r,T, = 214,6 ± 2 kJ/mol und δS°r,T = 263,2 ± 4J/K · mol.In der Gasphase treten keine meßbaren Mengen ReO3 auf. ReO2 zersetzt sich oberhalb 800°C nach \documentclass{article}\pagestyle{empty}\begin{document}$$ 7/2\,{\mathop{\rm Re}\nolimits} {\rm O}_{\rm 2},{\rm f}\,{\rm = }\,{\rm 3/2}\,{\rm Re, f}\,{\rm + }\,{\rm Re}_{\rm 2} {\rm O}_{\rm 7},{\rm g} $$\end{document} mit δH°r,T = 387,0 ± 8,4 kJ/mol und δS°r,T = 289,1 ± 12,5 J/K · mol.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19855230417
