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The Melting Temperature, Vapor Density, and Vapor Pressure of Molybdenum Pentafluoride.

PB277326

Publication Date	1977
Personal Author	Krause, R. F.; Douglas, T. B.
Page Count	15
Abstract	A sample of MoF5 was prepared by reaction of MoF6(g) and Mo(c). Melting curves of temperature against time established the melting temperature at zero impurity to be 318.85 K, the enthalpy of fusion to be 6.1 kJ/mol (+ or - 5 per cent), and the cryoscopic impurity of the sample to be 0.15 mole per cent. In the presence of MoF6(g), which was added to suppress disproportionation, the vapor density of MoF5 over the liquid was measured by the transpiration method at 343, 363, and 383 K, the total MoF5 that evaporated being determined by permanganate titration. The total vapor pressure of MoF5 oligomers over the liquid was measured by a simple static method at 373 and 392 K, while melting temperatures were taken alternately to monitor possible contamination of the sample. Although the vapor pressures were adjusted for disproportionation, solution of MoF6 in MoF5, and wall adsorption of MoF6, their percentage uncertainty is probably several times that of the vapor densities. A combination of the two properties indicates the average extent of association of the saturated vapor to be near 2, which is the value for the dimer species (MoF5)2.
Keywords	Melting point Vapor pressure Density(Mass/volume) Molybdenum halides Fluorides Thermodynamic properties Reprints Molybdenum pentafluoride
Source Agency	National Institute of Standards and Technology Air Force
NTIS Subject Category	99F - Physical & Theoretical Chemistry
Corporate Authors	National Bureau of Standards, Washington, D.C.; Air Force Office of Scientific Research, Bolling AFB, D.C.
Supplemental Notes	Sponsored in part by Air Force Office of Scientific Research, Bolling AFB, D.C.
Document Type	Journal Article
Title Note	Final rept.
NTIS Issue Number	197811

The Melting Temperature, Vapor Density, and Vapor Pressure of Molybdenum Pentafluoride.

The Melting Temperature, Vapor Density, and Vapor Pressure of Molybdenum Pentafluoride.
PB277326

Publication Date	1977
Personal Author	Krause, R. F.; Douglas, T. B.
Page Count	15
Abstract	A sample of MoF5 was prepared by reaction of MoF6(g) and Mo(c). Melting curves of temperature against time established the melting temperature at zero impurity to be 318.85 K, the enthalpy of fusion to be 6.1 kJ/mol (+ or - 5 per cent), and the cryoscopic impurity of the sample to be 0.15 mole per cent. In the presence of MoF6(g), which was added to suppress disproportionation, the vapor density of MoF5 over the liquid was measured by the transpiration method at 343, 363, and 383 K, the total MoF5 that evaporated being determined by permanganate titration. The total vapor pressure of MoF5 oligomers over the liquid was measured by a simple static method at 373 and 392 K, while melting temperatures were taken alternately to monitor possible contamination of the sample. Although the vapor pressures were adjusted for disproportionation, solution of MoF6 in MoF5, and wall adsorption of MoF6, their percentage uncertainty is probably several times that of the vapor densities. A combination of the two properties indicates the average extent of association of the saturated vapor to be near 2, which is the value for the dimer species (MoF5)2.
Keywords	Melting point Vapor pressure Density(Mass/volume) Molybdenum halides Fluorides Thermodynamic properties Reprints Molybdenum pentafluoride
Source Agency	National Institute of Standards and Technology Air Force
NTIS Subject Category	99F - Physical & Theoretical Chemistry
Corporate Authors	National Bureau of Standards, Washington, D.C.; Air Force Office of Scientific Research, Bolling AFB, D.C.
Supplemental Notes	Sponsored in part by Air Force Office of Scientific Research, Bolling AFB, D.C.
Document Type	Journal Article
Title Note	Final rept.
NTIS Issue Number	197811