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 iodide, CuI






The preparation of Cuprous iodide, CuI, can be effected by methods analogous to those adopted for cuprous bromide. Among them are the interaction of finely divided copper and either iodine or concentrated hydriodic acid under the influence of heat.

The iodide is also produced by the action of sulphur dioxide on an aqueous solution of cupric sulphate and potassium iodide:

2CuSO4 + 4KI = 2CuI + 2K2SO4 + I2; SO2 + 2H2O + I2 = H2SO4 + 2HI.

The hydrogen iodide produced reacts with another portion of the cupric sulphate, the whole reaction corresponding with the equation

4CuSO4 + 4KI + 2SO2 + 4H2O = 4CuI + 2K2SO4 + 4H2SO4.

Ferrous sulphate can also be employed as reducer:

2CuSO4 + 2KI + 2FeSO4 = 2CuI + Fe2(SO4)3 + K2SO4.

The iodide can also be prepared from aqueous solutions of cupric sulphate and potassium iodide without subsequent reduction, the liberated iodine being removed by agitation with alcohol.

The best method of preparing cuprous iodide depends on the interaction of cold solutions of cupric sulphate (30 grams), potassium iodide (16 grams), and sodium thiosulphate (25 grams):

2CuSO4 + 2KI + 2Na2S2O3 = 2CuI + K2SO4 + Na2S4O6 + Na2SO4.

After repeated washing with water and with alcohol, the precipitated iodide is dried in a vacuum-desiccator over sulphuric acid.

The white powder obtained by the last process gradually acquires a slight brown tint, but the salt does not exhibit phototropy. Cuprous iodide crystallizes in white tetrahedra, melting at 590° C. according to Monkemeyer, or 628° C. according to Carnelley and O'Shea. Carnelley and Williams give the boiling-point as between 759° and 772° C. Its density is D414.5 = 5.672. The heat of formation of the simple molecule CuI from solid copper and solid iodine is 16.26 Cal.

Solutions of cuprous iodide in hydrochloric acid and in ammonia readily absorb carbon monoxide, the maximum absorption corresponding with one molecule of the gas to each atom of copper. The salt also dissolves in solutions of sodium sulphate and potassium cyanide, but the liquids produced do not absorb carbon monoxide.

Several complex derivatives of cuprous iodide have been prepared, including CuI,2NH3; 2CuI,2NH4I,H2O2; CuI,NH4I,4(NH4)2S2O3; 2CuI,(NH4)2S2O3,H2O; 2CuI,K2S2O3,H2O; and 2CuI,Na2S2O3,H2O.


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