Chemical elements
    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 sulphate, Cu2SO4

Cuprous sulphate, Cu2SO4, cannot be isolated by methods analogous to those employed for the preparation of the cuprous halides. Metallic copper dissolves in solutions of cupric sulphate containing free sulphuric acid, an equilibrium corresponding with the scheme

2CuCu•• + Cu

being attained. At ordinary temperatures the proportion of cuprous sulphate formed is small, but it is increased by rise of temperature.

Cuprous sulphate was first isolated by Recoura by the interaction of molecular proportions of cuprous oxide and methyl or ethyl sulphate at 160° C. in absence of moisture. The presence of excess of the alkyl sulphate induces decomposition of the product with formation of cupric sulphate:

Cu2O + (CH3)2SO4 = Cu2SO4 + (CH3)2O.

The salt is dried by washing with ether and placing in a vacuum-desiccator over sulphuric acid.

The sulphate is a light-grey powder, instantly decomposed by water in accordance with the equation

[Cu2SO4] + Aq. = CuSO4 (dissolved) + [Cu] + 21 Cal.

Since the heat of solution of anhydrous cupric sulphate in water is 15.8 Cal., the transformation of a gram-molecule of cuprous sulphate into cupric sulphate and copper is attended by the evolution of 5.2 Cal., the reaction being exothermic. The formation of cuprous sulphate is an endothermic reaction, although that of each of the other cuprous salts is accompanied by evolution of heat. At ordinary temperatures, in presence of dry air, cuprous sulphate is stable, but contact with moist air induces a very slow decomposition. The presence of ether renders the action of moist air very rapid, the black mass formed being converted by water into a solution of cupric sulphate and a black oxide with properties similar to those of the product assumed by Rose to be a suboxide, Cu4O. Heating at 200° C. in air oxidizes cuprous sulphate to a brownish-black mixture of cupric oxide and cupric sulphate.

Cuprous sulphate dissolves in concentrated hydrochloric acid and in concentrated ammonium hydroxide. The ammoniacal solution yields a colourless, crystalline compound, Cu2SO4,4NH3,H2O, decomposed by water into metallic copper and an ammoniacal cupric compound. Cuprous sulphate is also dissolved to a slight extent by glacial acetic acid. The deep-violet solution thus produced is rapidly oxidized by air to a blue liquid, from which crystals of an acid cupric acetate are deposited.

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