Chemical elements
  Carbon
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Methane
      Ethylene
      Acetylene
      Coal-Gas
      Carbon Tetrafluoride
      Tetrafluoromethane
      Carbon Tetrachloride
      Tetrachloromethane
      Carbon Tetrabromide
      Tetrabromomethane
      Carbon Tetraiodide
      Tetraiodomethane
      Carbon Oxychloride
      Carbonyl Chloride
      Phosgene
      Carbon Oxybromide
      Carbonyl Bromide
      Carbon Suboxide
      Carbon Monoxide
      Carbon Dioxide
      Percarbonic Acid
      Carbamic Acid
      Carbamide
      Urea
      Carbon Disulphide
      Carbonyl Sulphide
      Carbon Oxysulphide
      Thiocarbonyl Chloride
      Thiocarbonic Acid
      Thiocarbamic acid
      Thiourea
      Thiocarbamide
      Perthiocarbonates
      Carbon Monosulphide
      Carbon Subsulphide
      Carbon Sulphidoselenide
      Carbon Sulphidotelluride
      Carbon Nitrides
      Cyanogen
      Dicyanogen
      Hydrocyanic Acid
      Prussic Acid
      Cyanogen Chloride
      Chlorocyanogen
      Cyanogen Bromide
      Bromocyanogen
      Cyanogen Iodide
      Iodocyanogen
      Polymerised Cyanogen Halides
      Cyanamide
      Cyanic Acid
      Cyanuric Acid
      Cyamelide
      Fulminic Acid
      Thiocyanic Acid
      Sulphocyanic Acid
      Isoperthiocyanic Acid
      Cyanogen Sulphide
      Thiocyanic Anhydride
    Diamonds
    Graphite
    Amorphous Carbon
    Coal

Carbon Tetrafluoride, CF4






Fluorine is the only halogen that will unite readily with carbon. Moissan has shown that in fluorine gas purified lampblack becomes incandescent, and wood-charcoal takes fire spontaneously, but that it is necessary to heat the denser forms of amorphous carbon to 50°-100° C. to induce combination; whilst graphite and gas-carbon react with fluorine only at a red heat, and diamond is unaffected at any temperature.

Carbon tetrafluoride results from the substitution of fluorine for hydrogen or halogen in methane or any of its halogen substitution products, but is best prepared by passing the vapour of carbon tetrachloride over silver fluoride heated in a metallic tube to 195°-200° C. Carbon tetrafluoride is a gas at ordinary temperatures and pressures; it is liquefied at 20° C. under four atmospheres, and at - 15° C. under one atmosphere pressure. It is slightly soluble in water, and very soluble in alcohol and ether; it reacts with the silica of heated glass, thus:

CF4 + SiO2 = CO2 + SiF4,

and with heated sodium forms fluoride with separation of carbon. It is absorbed by alcoholic potash, being gradually converted into a mixture of potassium fluoride and carbonate.

It is noteworthy that no complex acid, H2CF6, analogous to H2SiF6, has been described; and indeed that carbon tetrafluoride, like the tetrachloride, is unacted on by water.


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