Chemical elements
  Copper
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
    Cuprous Compounds
      Cuprous hydride
      Cuprous fluoride
      Cuprous chloride
      Cuprous bromide
      Cuprous iodide
      Copper suboxide
      Cuprous oxide
      Cuprous hydroxide
      Cuprous sulphide
      Cuprous sulphite
      Cuprous sulphate
      Cuprous selenide
      Cuprous telluride
      Cuprous nitride
      Cuprous phosphide
      Cuprous arsenides
      Cuprous carbide
      Cuprous acetylide
      Cuprous carbonate
      Cuprous cyanide
      Cuprous thiocyanate
      Cuprous silicide
      Cuprous silicofluoride
      Ammonio-cuprous Derivatives
      Carbonyl cuprous sulphate
    Complex Copper Compounds
    Cupric Compounds
    PDB 1a2v-1bxu
    PDB 1bxv-1fwx
    PDB 1g3d-1j9t
    PDB 1jcv-1mfm
    PDB 1mg2-1paz
    PDB 1pcs-1sii
    PDB 1sjm-1w6w
    PDB 1w77-2afn
    PDB 2ahk-2dv6
    PDB 2dws-2ggp
    PDB 2ghz-2mta
    PDB 2nrd-2vm3
    PDB 2vm4-2yah
    PDB 2yam-3bkt
    PDB 3bqv-3fyi
    PDB 3g5w-3mie
    PDB 3mif-3t6v
    PDB 3t6w-9pcy

Cuprous bromide, CuBr






Several methods are available for the preparation of Cuprous bromide, CuBr, examples being the interaction of copper-turnings and an aqueous solution of cupric bromide at its boiling-point, and the direct synthesis from bromine and excess of copper. The most convenient process is that of Sandmeyer. A solution of cupric sulphate (12.5 grams), potassium bromide (36 grams), and concentrated sulphuric acid (6 c.c.) in water (80 c.c.) is boiled under reflux with copper-turnings until the solution has become colourless. After precipitation by filtration through asbestos into a large excess of water covered with a layer of ether, the cuprous bromide is allowed to settle. The mother-liquor is then syphoned off, and the salt is washed on a filter with water, alcohol, and ether, and dried in a vacuum- desiccator over sulphuric acid.

The pure bromide is a white substance, but gradually develops a yellow tint, and on exposure to sunlight it acquires a bluish colour. In phototropic character it resembles cuprous chloride, exposure to light changing its colour through dark green to dark copper. If the duration of the action of the light has been limited to a few minutes, keeping in the dark for 30 hours reverses the colour changes. The melting-point of the bromide is given by Monkemeyer as 480° C., and by Carnelley and Williams as 504° C. The boiling-point is between 861° and 954° C., and the density is given by Bodeker as 4.72.

Cuprous bromide is insoluble in water. Its solutions in hydrochloric acid, hydrobromic acid, and ammonium hydroxide readily absorb carbon monoxide. The maximum absorption for the ammoniacal solution corresponds with one molecule of carbon monoxide to each atom of copper. When prepared in absence of air, the solution in ammonium hydroxide is colourless, but on contact with oxygen it develops a blue colour. The liquid obtained by dissolving cuprous bromide in an aqueous solution of sodium chloride or of sodium thiosulphate does not absorb carbon monoxide.

The heat of formation of the simple molecular compound CuBr from solid copper and liquid bromine is 24.985 Cal.

The complex derivatives of cuprous bromide include CuBr,NH3 (Richards and Merigold); CuBr,2NH3 (Saglier); and CuBr,3NH3 (Richards and Merigold).


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