Chemical elements
    Physical Properties
    Chemical Properties
      Uranium Difluoride
      Uranium Tetrafluoride
      Uranous Oxyfluoride
      Uranium Hexafluoride
      Uranyl Fluoride
      Uranium Trichloride
      Uranium Tetrachloride
      Uranium Pentachloride
      Uranyl Chloride
      Uranyl Chlorate
      Uranyl Perchlorate
      Uranium Tetrabromide
      Uranyl Bromide
      Uranium Tetra-iodide
      Uranyl Iodide
      Uranyl Iodate
      Uranous Oxide
      Uranous Hydroxide
      Uranium Pentoxide
      Urano-uranic Oxide
      Uranium Trioxide
      Ammonium Diuranate
      Ammonium Hexa-uranate
      Hydroxylamine Uranate
      Hydroxylamine Potassio-uranate
      Barium Uranate
      Barium Diuranate
      Bismuth Uranate
      Iron Uranate
      Lithium Uranate
      Potassium Uranate
      Potassium Diuranate
      Potassium Tetra-uranate
      Potassium Hexa-uranate
      Rubidium Uranate
      Silver Diuranate
      Sodium Uranate
      Sodium Diuranate
      Sodium Triuranate
      Sodium Penta-uranate
      Strontium Uranate
      Zinc Uranate
      Peruranic acid
      Ammonium Peruranate
      Barium Peruranates
      Lithium Peruranate
      Nickel Peruranate
      Potassium Peruranate
      Sodium Peruranates
      Uranium Monosulphide
      Uranium Sesquisulphide
      Uranium Disulphide
      Uranium Oxysulphide
      Uranyl Sulphide
      Uranium Sulphite
      Uranyl Sulphite
      Complex Uranyl Sulphites
      Uranium Sulphate
      Uranium Dithionates
      Uranyl Sulphate
      Uranyl Pyrosulphate
      Uranyl Thiosulphate
      Uranyl Dithionate
      Uranium Sesquiselenide
      Uranium Diselenide
      Uranyl Selenide
      Uranyl Selenite
      Uranyl Selenate
      Uranium Telluride
      Uranium Nitrides
      Uranous Nitrate
      Uranyl Nitrate
      Uranium Monophosphide
      Uranous Phosphide
      Uranyl Hypophosphite
      Uranyl Phosphite
      Uranous Phosphates
      Uranyl Phosphates
      Complex Uranyl Phosphates
      Uranyl Aminophosphates
      Uranous Arsenide
      Uranyl Metarsenite
      Uranous Arsenate
      Uranyl Arsenates
      Complex Uranyl Arsenates
      Uranous Antimonide
      Uranous Antimonate
      Uranium Carbide
      Complex Uranyl Carbonates
      Ammonium Uranyl Carbonate
      Calcium Uranyl Carbonate
      Potassium Uranyl Carbonate
      Sodium Uranyl Carbonate
      Thallium Uranyl Carbonate
      Potassium Uranyl Ferrocyanide
      Uranyl Platinocyanide
      Uranyl Cyanate
      Uranyl Thiocyanate
      Uranium Silicide
      Uranium Boride
      Uranyl Perborate
    PDB 1anv-3pu4

Uranium Hexafluoride, UF6

Uranium Hexafluoride, Uranic Fluoride, UF6, is the only known compound of hexavalent uranium (with the possible exception of the boride in which the condition of the uranium is not established) which does not contain oxygen. It was first prepared by Ruff and Heinzelmann by the action of fluorine on uranium pentachloride at -40° C. The action proceeds as already described (see equation above), and the volatile hexafluoride is distilled off from the tetrafluoride. The pentachloride, when acted upon by dry hydrogen fluoride, yields a compound, UF5.xHF, which breaks up on distillation into the tetra- and hexa- fluorides, but this method of preparation is less convenient than the preceding one owing to the difficulty of separating the hexafluoride from hydrogen fluoride. Uranium carbide reacts with fluorine in presence of a little chlorine at -70°C., with formation of the hexafluoride.

Uranium hexafluoride yields glistening, colourless or pale yellow, monoclinic 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:

Temperature, ° C56.248454137
Pressure, mm764.6521.2410.1406.1298.2

The crystals melt at 69.2° C. at which temperature the vapour pressure is (by extrapolation) 1490 mm. or about 2 atmospheres. The vapour density at 448° C. is 11.7 (air = l), corresponding to a molecular weight of 338 (the theoretical value being 12.16).

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 last case depositing carbon. It reacts more slowly with carbon disulphide, paraffin, chloroform, and nitrobenzene. It dissolves readily in tetrachlorethane. It attacks glass in presence of a trace of moisture, forming silicon tetrafluoride and uranium oxyfluoride. It is decomposed by nitric acid. Ammonia forms ammonium uranate and fluoride. It is reduced by most non-metals and metals, except gold and platinum. Sulphur forms the disulphide, US2, and uranous fluoride, and a gas is evolved which appears to be a new fluoride of sulphur. It is stable in presence of dry air, oxygen, nitrogen, carbon dioxide, chlorine, bromine, or iodine.

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