Chemical elements
  Gold
    Isotopes
    Energy
    Production
    Extraction
    Application
    Physical Properties
    Chemical Properties
      Aurous fluoride
      Aurous chloride
      Aurous bromide
      Aurous iodide
      Aurous oxide
      Aurous sulphide
      Aurous thiosulphate
      Aurous Derivatives of Nitrogen
      Aurous cyanide
      Potassium aurothiocyanate
      Ammonia and Aurous Halides
      Gold dichloride
      Gold dibromide
      Gold monoxide
      Gold monosulphide
      Gold monosulphate
      Nitride of Bivalent Gold
      Auric chloride
      Aurichloric Acid
      Auric bromide
      Auribromic Acid
      Auric iodide
      Auri-iodic Acid
      Auric iodate
      Auric hydroxide
      Auric sulphide
      Auric sulphate
      Acid auryl sulphate
      Auric selenide
      Auric selenate
      Auric telluride
      Gold and Nitrogen
      Auric nitrates
      Gold and Phosphorus
      Gold arsenides
      Auric selenide
      Auric antimonide
      Auric cyanide
      Salts of Auricyanic Acid
      Double Salts of Auric thiocyanate
      Gold carbide
      Gold and Silicon
    PDB 1a52-4acl

Aurous sulphide, Au2S






The pure sulphide can be prepared by saturation of a solution of potassium aurocyanide with hydrogen sulphide, and precipitation of the salt by acidifying the solution with hydrochloric acid. It is not produced by the action of hydrogen sulphide on a hot solution of auric chloride, as supposed by Berzelius. The moist substance has a steel-grey colour; when dried, it becomes brownish black. When freshly prepared, the sulphide dissolves in water to a colloidal solution, from which it is reprecipitated by addition of hydrochloric acid. The sulphide is unaffected by dilute acids, but is decomposed by powerful oxidizers such as aqua regia and chlorine. It is readily dissolved by solutions of polysulphides, and less readily by those of monosulphides. It also dissolves in a solution of potassium cyanide. With sodium sulphide and with potassium sulphide, aurous sulphide forms double sulphides of the type NaAuS.


Complex Derivatives of Aurous sulphite

Although aurous sulphite itself has not been isolated, double sulphites of aurous gold with sodium, potassium, ammonium, and barium have been obtained. The sodium salt is formed by the interaction of auric chloride and sodium sulphite in alkaline solution, or by the action of sodium hydrogen sulphite on a boiling solution of a gold salt, or by that of sulphurous acid on a similar solution at 30° to 50° C. It has the formula Au2SO3,3Na2SO3,3H2O or Na3Au(SO3)2,1½H2O, containing the complex anion Au(SO3)2''', since it does not display the reactions characteristic of sulphites. It is readily soluble in water.

The corresponding potassium salt forms white needles, and the barium salt is a purple-red, amorphous substance. The constitution of the ammonium salt produced by the interaction of auric chloride and an ammomacal solution of ammonium sulphite is uncertain, but is given as

2Au2SO3,(NH4)2SO3,6NH3,4H2O,
or
5Au2SO3,2(NH4)2SO3,1ONH3,4H2O.
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