Chemical elements
    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

Auric chloride, AuCl3

Under certain conditions gold is converted by chlorine into auric chloride. At ordinary temperatures such reagents as chlorine-water, aqua regia, and the higher chlorides of manganese, nickel, and cobalt effect this change. At 300° C. the dry gas transforms the metal into the chloride, the product subliming in reddish, bulky crystals. An aqueous solution can be prepared by the action of water on the dichloride, or on aurous chloride:

3AuCl2 = 2AuCl3+Au.
3 AuCl = AuCl3+2Au.

Spontaneous evaporation of the solution of the chloride yields dark, orange-yellow crystals of the dihydrate, AuCl3,2H2O, which changes to the anhydrous salt on exposure to the air. The monohydrate, AuCl3,H2O, is supposed to exist in solution in the form of an acid, H2AuCl3O. With silver carbonate this acid yields a yellowish silver salt, Ag2AuCl3O. The constitution of the acid and of its salts is a matter of uncertainty.

On rapid evaporation of a solution of auric chloride in an acidic solution capable of generating chlorine, and subsequently drying the product at 150° C., the salt is obtained in anhydrous form as a dark-brown crystalline mass, reducible to a reddish-brown powder. Its melting-point in an atmosphere of chlorine or in a sealed tube is 287° to 288° C., and its density is 3.9. On heating in a closed space it dissociates, the reaction beginning at 190° to 200° C.:

AuCl3AuCl + Cl2.

Under a pressure of two atmospheres in contact with chlorine there is no separation of metallic gold, even at the melting-point.

Auric chloride is reduced by carbon in accordance with the equation

4AuCl3 + 6H2O+3C = 4Au +12HCl+3CO2.

It is also reduced to metallic gold by phosphorous acid and sodium hypophosphite, and by cupric sulphide in accordance with the equation

CuS+2AuCl3+3H2O+O = 2Au+CuSO4+6HCl.

A test of the purity of the salt is its complete solubility in ether. It is unaffected by the prolonged action of radium bromide.

In dissolving alloys of gold and silver in aqua regia in presence of ammonium chloride and nitrate, purplish-brown crystals of the formula

3AgCl, 4AuCl3, 8NH4Cl

are sometimes obtained as a by-product.

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