Uranium hexafluoride, crystal

Uranium hexafluoride yflelds jglistening, colourless or pale yellow, monoclinie crystals, which fume in the air and sublime under reduced pressure at ordinary temperature. It boils at 56-2° C., and the calculated mean latent heat of evaporation between 42° and 57° C. is 29 4 calories per gram ( = 10360 calories per gram molecule). The variation of the boiling-point with the vapour pressure is as follows ... 

The crystals have density at 20-7° C., 4-68. They are very hygroscopic and soluble in water. Chemically, uranium hexafluoride is highly reactive, vigorously attacking alcohol, ether, or benzene, in the... 

Uranium hexafluoride is important because it is used to separate U from 2 U by means of the diffusion of this compound. The pale yellow crystals melt at 69° under 2 atmospheres pressure and have a vapour pressure of 760 mm at 56°, so that they are very easily sublimed. The hexafluoride is made by the action of fluorine on the metal in the presence of some chlorine otherwise UF4 is formed. Fluorination by CIF3 is also employed. UFg is stable to air, oxygen, chlorine and iodine, but is easily hydrolysed and readily reduced to the tetrafluoride by hydrogen at the ordi-... 

Uranium hexafluoride has a molecular formula of UF. It is a colorless, volatile crystal that sublimes and reacts vigorously with water. It is highly corrosive and is a radiation risk. The four-digit UN identification number for fissile material containing more than 1% of uranium 235 is 2977 for lower specific activity, the number is 2978. Uranium hexafluoride is used in a gaseous diffusion process for separating isotopes of uranium. 

Butler JE and Hutchison, Jr. CA 1981 Electron paramagnetic resonance and electron nuclear double resonance of 237-neptunium hexafluoride in uranium hexafluoride single crystals. J. Chem. Phys. 74(6), 3102-3119. 

A laboratory preparation is the reaction of uranium metal and CIF3.20 The hexafluoride forms colorless crystals (mp 64.1°C) with a vapor pressure of 115 mm Hg at 25°C. It is a powerful fluorinating agent (e.g., it converts CS2 to SF4) and is rapidly hydrolyzed by water. The hexafluoride is also used to make UF4 and UF5 by the following reactions ... 

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