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

Carbamic Acid, HOCONH2






Carbamic Acid, HO-CO-NH2, the half-amide of carbonic acid, is unknown, but several of its salts exist, the most important of which is ammonium carbamate, NH4O-CO-NH2. This salt is formed by the union of carbon dioxide with ammonia:

CO2 + 2NH3 = NH4-CO2-NH2,

which is best effected by passing the mixed, dry gases through absolute alcohol. Ammonium carbamate also occurs, together with ammonium bicarbonate, in commercial carbonate of ammonia, prepared by sublimation when a moistened mixture of calcium carbonate and ammonium sulphate is heated; it gradually sublimes at atmospheric temperature from this compound, and is frequently deposited in transparent prisms upon the neck of the bottle containing the commercial salt. The carbamate may also be obtained from the commercial salt by acting upon it for thirty or forty hours with saturated solution of ammonia at 20°-25° C.; but dilute ammonia solution, like water, converts carbamate in solution into normal carbonate. When vaporised, ammonium carbamate is completely dissociated into ammonia and carbon dioxide. This is shown by the vapour density, which is 0.892 (air = 1) between 37° C. and 100° C. Recombination on cooling is slow, owing to the necessary intramolecular change. Sodium and potassium carbamates and a basic calcium salt, NH2-CO-OCa(OH), are known. Ethyl carbamate, NH2-CO-OC2H5, is urethane.
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