Chemical elements
  Tungsten
    Isotopes
    Energy
    Production
    Preparation
    Application
    Physical Properties
    Chemical Properties
    Compounds
      Tungsten Hexafluoride
      Tungsten Oxyfluorides
      Tungsten Dichloride
      Double Chlorides of Trivalent Tungsten
      Tungsten Tetrachloride
      Tungsten Pentachloride
      Tungsten Hexachloride
      Tungsten Oxychlorides
      Tungsten Dibromide
      Tungsten Pentabromide
      Tungsten Hexabromide
      Tungsten Chlorobromides
      Tungsten Oxybromides
      Tungsten Di-iodide
      Tungsten Tetra-iodide
      Tungsten Dioxide
      Ditungsten Pentoxide
      Tungsten Trioxide
      Tungstic Acid
      Aluminium Tungstates
      Ammonium Tungstates
      Antimony Tungstates
      Barium Tungstates
      Normal Bismuth Tungstate
      Cadmium Tungstates
      Calcium Tungstates
      Cerium Tungstate
      Chromium Tungstates
      Cobalt Tungstates
      Copper Tungstates
      Indium Tungstate
      Iron Tungstates
      Lanthanum Tungstate
      Lead Tungstates
      Lithium Tungstates
      Magnesium Tungstates
      Manganese Tungstates
      Mercury Tungstates
      Neodymium Tungstate
      Nickel Tungstates
      Platinum Tungstates
      Potassium Tungstates
      Praseodymium Tungstate
      Rubidium Tungstates
      Samarium Tungstate
      Silver Tungstates
      Sodium Tungstates
      Strontium Tungstates
      Thallium Tungstates
      Tin Tungstates
      Uranium Tungstate
      Ytterbium Tungstates
      Yttrium Tungstate
      Zinc Tungstates
      Metatungstic Acid
      Ammonium Metatungstate
      Barium Metatungstate
      Cadmium Metatungstate
      Calcium Metatungstate
      Cerium Metatungstate
      Cobalt Metatungstate
      Lead Metatungstate
      Magnesium Metatungstate
      Mercurous Metatungstate
      Nickel Metatungstate
      Potassium Metatungstate
      Rubidium Metatungstate
      Samarium Metatungstate
      Silver Metatungstate
      Sodium Metatungstate
      Strontium Metatungstate
      Thallous Metatungstate
      Zinc Metatungstate
      Pertungstic Acid
      Tungsten Bronzes
      Potassium Tungsten Bronze
      Lithium Tungsten Bronze
      Lithium Potassium Tungsten Bronze
      Sodium tungsten bronzes
      Tungsten Disulphide
      Tungsten Trisulphide
      Thiotungstates
      Tungsten Diselenide
      Tungsten Triselenide
      Tungsten Phosphides
      Tungsten Diphosphide
      Tritungsten Tetraphosphide
      Tungsten Monophosphide
      Tungsten Subphosphide
      Phosphotungstic Acids
      12-Tungstophosphoric Acid
      11-Tungstophosphates
      21:2-Tungstophosphoric Acid
      10-Tungstophosphoric Acid
      9-Tungstophosphoric Acid
      17:2-Tungstophosphates
      3-Tungstophosphates
      Hypophosphotungstates
      Tungsten Diarsenide
      Tungsten Chloro-arsenide
      12-Tungsto-arsenates
      11-Tungsto-arsenates
      9-Tungsto-arsenic Acid
      17:2-Tungsto-arsenates
      Tungsto-arsenites
      Tritungsten Carbide
      Ditungsten Carbide
      Tungsten Monocarbide
      Tungsten Iron Carbides
      Tungstocyanic Acid
      Ammonium Tungstocyanide
      Calcium Tungstocyanide
      Cadmium Tungstocyanide
      Caesium Tungstocyanide
      Lead Tungstocyanide
      Magnesium Tungstocyanide
      Manganese Tungstocyanide
      Potassium Tungstocyanide
      Rubidium Tungstocyanide
      Silver Tungstocyanide
      Sodium Tungstocyanide
      Strontium Tungstocyanide
      Thallium Tungstocyanide
      Zinc Tungstocyanide
      Tungsticyanic Acid
      Tungsten Sesquisilicide
      Tungsten Disilicide
      Tungsten Trisilicide
      12-Tungstosilicic Acid
      Iso-12-tungstosilicic Acid
      10-Tungstosilicates
      Tungsten Boride
      12-Tungstoboric Acid
      Iso-12-tungstoboric Acid
    Alloys
    PDB 1aor-2rav
    PDB 2rb5-6fit

Ditungsten Pentoxide






The Blue Oxide of Tungsten (Ditungsten Pentoxide) may be formed by oxidation of the dioxide, or by reduction of the trioxide. It is thus an intermediate oxide, and since it is itself prone to oxidation, it is difficult to isolate in a pure condition, and it is doubtful whether it has yet been so obtained. Our knowledge of its composition and properties is therefore limited. It is generally known as the " blue oxide" of tungsten, and there is evidence of pentavalent tungsten, but the blue product may also be regarded as essentially tungsten tungstate.

The formation of a blue compound by reduction of tungsten trioxide was first observed by Berzelius, and the compound was first prepared by Malaguti by heating the trioxide at 250° to 300° C. in a current of hydrogen. Carbon monoxide may be used instead of hydrogen. The blue oxide may also be obtained by cautiously heating ammonium para-tungstate in a closed crucible, by the electrolysis of fused sodium tungstate or of a boiling solution of a tungstate in hydrochloric acid, by decomposition of tungsten pentachloride or pentabromide by means of water, or by reduction of an acidified solution of a tungstate by means of zinc or stannous chloride. The product is a powder of which the colour varies from greenish blue to deep blue. It is readily converted to the trioxide by heating in oxygen or air. Its magnetic susceptibility is 0.755. When prepared in the wet way it is readily oxidised by nitric acid, but the product obtained in the dry way resists this reagent.

A similar blue compound was prepared by Allen and Gottschalk by heating on a water-bath a mixture of tungsten trioxide and stannous chloride in hydrochloric acid solution, or by heating the trioxide with concentrated hydriodic acid in a sealed tube at 200° C. The product was oxidised on standing in air, was insoluble in hydrochloric acid, but soluble in alkalies with evolution of hydrogen. Its composition appeared to be W5O14.H2O. It reacted with ammonia, yielding some ammonium tungstate and a brownish-purple residue of composition W3O8.H2O.

A colloidal solution of the blue oxide, known as tungsten blue, may be obtained by the electrolytic reduction of an acidified tungstate solution, or by first saturating a solution of metatungstic acid with hydrogen sulphide and then neutralising by means of ammonia or ammonium sulphide. The solution, when freshly prepared, is optically void, but, on standing, a luminous cone gradually appears. Under the influence of the electric current the colloid moves towards the anode. The composition of the dissolved oxide, according to Leiser, is W4O11. The solution may be used for dyeing silk, and also, but not so satisfactorily, cotton and wool.


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