Chemical elements
  Arsenic
      Occurrence
      Ubiquity
      History
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Aluminium Arsenide
      Antimony Arsenides
      Barium Arsenide
      Bismuth Arsenides
      Cadmium Arsenides
      Calcium Arsenide
      Cerium Arsenide
      Chromium Arsenides
      Cobalt Arsenides
      Copper Arsenides
      Gold Arsenides
      Iridium Arsenide
      Iron Arsenides
      Lead Arsenides
      Lithium Arsenide
      Magnesium Arsenide
      Manganese Arsenides
      Mercury Arsenides
      Molybdenum Arsenide
      Nickel Arsenides
      Niobium Arsenide
      Palladium Di-arsenide
      Platinum Arsenides
      Potassium Arsenides
      Rhodium Arsenide
      Ruthenium Arsenide
      Silver Arsenides
      Sodium Arsenide
      Strontium Arsenide
      Thallium Arsenide
      Tin Arsenides
      Tungsten Arsenide
      Uranium Arsenide
      Zinc Arsenides
      Arsenic Subhydride
      Arsenic Monohydride
      Arsenic Trihydride
      Arsenic Trifluoride
      Arsenic Pentafluoride
      Arsenic Nitrosyl Hexafluoride
      Arsenic Trichloride
      Arsenic Oxychloride
      Arsenic Pentachloride
      Arsenic Tribromide
      Arsenic Oxybromide
      Arsenic Moniodide
      Arsenic Diiodide
      Arsenic Triiodide
      Arsenic Pentiodide
      Arsenic Suboxide
      Arsenious Oxide
      Aluminium Arsenite
      Ammonium Arsenites
      Antimony Arsenite
      Barium Arsenites
      Beryllium Arsenite
      Bismuth Arsenite
      Cadmium Arsenites
      Calcium Arsenites
      Chromic Arsenite
      Cobalt Arsenites
      Copper Arsenites
      Gold Arsenites
      Iron Arsenites
      Lead Arsenites
      Lithium Arsenite
      Magnesium Arsenites
      Manganese Arsenites
      Mercury Arsenites
      Nickel Arsenites
      Palladium Pyroarsenite
      Platinum Arsenites
      Potassium Arsenites
      Arsenites of Rare Earth Metals
      Rubidium Metarsenite
      Silver Arsenites
      Sodium Arsenites
      Strontium Arsenites
      Thallous Orthoarsenite
      Tin Arsenites
      Titanyl Tetrarsenite
      Tungsto-arsenites
      Uranyl Metarsenite
      Zinc Arsenites
      Zirconium Arsenite
      Arsenic Tetroxide
      Arsenic Pentoxide
      Aluminium Arsenates
      Ammonium Arsenates
      Barium Arsenates
      Beryllium Arsenates
      Bismuth Arsenates
      Cadmium Arsenates
      Caesium Arsenate
      Calcium Arsenates
      Chromium Arsenates
      Cobalt Arsenates
      Copper Arsenates
      Hydroxylamine Orthoarsenate
      Iron Arsenates
      Lead Arsenates
      Lithium Arsenates
      Magnesium Arsenates
      Manganese Arsenates
      Mercury Arsenates
      Molybdenum Arsenates
      Nickel Arsenates
      Palladium Arsenate
      Platinic Arsenate
      Potassium Arsenates
      Rare Earth Metals Arsenates
      Rhodium Arsenate
      Rubidium Arsenates
      Silver Arsenates
      Sodium Arsenates
      Strontium Arsenates
      Thallium Arsenates
      Thorium Arsenates
      Tin Arsenates
      Titanyl Arsenate
      Tungsto-arsenic Acids
      Uranium Arsenates
      Vanado-arsenates
      Zinc Arsenates
      Zirconium Arsenates
      Perarsenates
      Arsenic and Sulphur
      Arsenic Subsulphide
      Tetrarsenic Trisulphide
      Arsenic Disulphide
      Arsenic Trisulphide
      Arsenic Pentasulphide
      Thioarsenates
      Ammonium Thioarsenates
      Antimony Thioarsenate
      Barium Thioarsenates
      Beryllium Thioarsenate
      Bismuth Thioarsenate
      Cadmium Thioarsenates
      Calcium Thioarsenates
      Cerium Thioarsenates
      Chromium Thioarsenate
      Cobalt Thioarsenate
      Copper Thioarsenates
      Gold Thioarsenates
      Iron Thioarsenates
      Lead Thioarsenates
      Lithium Thioarsenates
      Magnesium Thioarsenates
      Manganese Thioarsenates
      Mercury Thioarsenates
      Molybdenum Thioarsenates
      Nickel Thioarsenates
      Platinic Thioarsenate
      Potassium Thioarsenates
      Silver Thioarsenates
      Sodium Thioarsenates
      Strontium Thioarsenates
      Thallium Orthothioarsenate
      Tin Thioarsenates
      Uranyl Thioarsenate
      Yttrium Thioarsenate
      Zinc Thioarsenates
      Zirconium Thioarsenate
      Trioxythioarsenic Acid
      Dioxydithioarsenic Acid
      Oxytrithioarsenic Acid
      Arsenic Monosulphatotrioxide
      Arsenic Disulphatotrioxide
      Arsenic Trisulphatotrioxide
      Arsenic Tetrasulphatotrioxide
      Arsenic Hexasulphatotrioxide
      Arsenic Octasulphatotrioxide
      Complex salts of Sulphato-compounds of Arsenic
      Arsenic Nitride
      Arsenic Imide
      Arsenic Amide
      Arsenic Phosphides
      Arsenic oxyphosphides
      Arsenic Phosphate
      Arsenic Thiophosphate
      Arsenic Tricarbide
      Arsenic Pentasilicide
      Boron Arsenate
    Detection of Arsenic
    Estimation of Arsenic
    Physiological Properties
    PDB 1b92-1ihu
    PDB 1ii0-1tnd
    PDB 1tql-2hmh
    PDB 2hx2-2xnq
    PDB 2xod-3htw
    PDB 3hzf-3od5
    PDB 3ouu-9nse

Copper Arsenides






Investigation of the freezing point curve of the system Cu-As confirms the existence of the two arsenides, Cu3As and Cu5As2, and there is evidence of the formation of the arsenide Cu2As. An arsenide of composition Cu3As2 is also known. The addition of arsenic to copper lowers the freezing point uniformly up to 14 per cent. As, when a steep fall occurs, reaching a minimum at 685° C. and yielding a eutectic mixture with 19.2 per cent. As corresponding approximately with Cu5As. As the proportion of arsenic is increased, the curve rises until, at 747° C., the first compound, Cu3As, containing 28.4 per cent. As, crystallises out. This is soon followed by the crystallisation at 807° C. of a second compound, Cu5As2, with 32.2 per cent. As. The freezing temperature then falls to a minimum at about 695° C., the eutectic mixture containing approximately 35 per cent, of As. With more arsenic the curve rises to 740° C. and, according to Hiorns, the arsenide, Cu2As, with 37.34 per cent. As, separates; Friedrich, however, could not obtain this compound. Beyond this point the curve begins to fall, but with more than 43 to 44 per cent. As, alloys could not be obtained by fusion, the excess of arsenic rapidly burning off.

Many arseniferous minerals contain arsenides of copper in a more or less pure state. They are found in various localities, but especially in Michigan and Chile. The more important are domeykite, Cu3As, and the allied minerals argento-domeykite, (Cu, Ag)3As, mohawkite, (Cu, Ni, Co)3As, and stibiodomeykite, Cu3(As, Sb); also algodonite, Cu6As, whitneyite and darwinite, Cu9As.

The influence of small quantities of arsenic on copper has already been described. The thermal conductivity of Cu-As alloys has been investigated, as also has the electrical behaviour at temperatures as low as 1.26° Abs., obtained by means of liquid helium; whether or not the alloys are supraconductive at these temperatures has not been definitely determined. The structure of various Cu-As alloys has been investigated by means of the X-rays.


Tri-copper Arsenide, Cu3As

Tri-copper Arsenide, Cu3As, has been prepared by melting a mixture of copper and arsenic under a layer of fused boric acid; by subjecting an intimate mixture of the elements in the required proportions to a pressure of 6500 atm.; by heating copper in arsenic vapour; by heating a mixture of copper and the hemi-arsenide, Cu2As; by the action of arsine on an aqueous solution of potassium cuprochloride, excess of Cu+ ion being avoided, otherwise precipitation of copper occurs; and by the action of hydrogen at high temperature and pressure on copper arsenate. By heating copper or a suitable alloy at about 600° C. in arsenic vapour Koenig obtained brilliant crystals corresponding in composition with the various forms of domeykite enumerated above.

The density of Cu3As is 6.7 to 7.7; the density calculated from crystallographic data is 8.22. The hardness is 3.0 to 3.5 on Mohs' scale. The specific heat is 0.0919. On heating, sublimation occurs at 345° to 370° C. The arsenide decomposes on strong heating. It is completely reduced when heated in hydrogen. It is stable towards hydrochloric acid, but is attacked by nitric acid.

The arsenide Cu5As2 has been prepared by passing a current of carbon dioxide and arsenic vapour over finely divided copper heated to the temperature of boiling sulphur; by the action of copper on arsenic trichloride or on arsenic dissolved in hydrochloric acid; and by the action of cuprous chloride on arsenic. Lustrous regular crystals of density 7.56 are obtained. These tarnish on exposure to air. When heated it loses arsenic and yields Cu3As, which at a higher temperature also decomposes. Cu5As2 dissolves in nitric acid. It is readily attacked by chlorine or bromine.

Hemi-arsenide, Cu2As

The hemi-arsenide, Cu2As, was described by Descamps as being formed when the black precipitate, resulting from the addition of arsenic to a solution of a copper salt, was fused under borax; according to Koenig, it is formed, with Cu3As, when arsenic vapour is passed over heated copper. Hiorns described it as being formed by fusing the elements together (see above), but Friedrich did not observe this to be the case. Koenig described it as a grey crystalline mass of density 7.71 at 21° C.

Tri-copper Di-arsenide, Cu3As2

Tri-copper Di-arsenide, Cu3As2, is formed when arsine acts on a solution of copper sulphate, or on dry copper sulphate or chloride; by subjecting a suitable mixture of the powdered elements to a pressure of 6500 atm.; by reducing cupric arsenite with fused potassium cyanide; or by the action at 100° C. of a solution of arsenic trichloride in hydrochloric acid on copper. It is obtained as a brittle bluish-grey crystalline mass of density 6.94.
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