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

Thiotungstates






By substituting sulphur for oxygen in tungstates the following types of compounds have been obtained: R2WO3S, R2WO2S2, R2WOS3, R2WS4. These are produced:
  1. By dissolving the hydrate of tungstic acid in an alkali hydro- sulphide.
  2. By the action of hydrogen sulphide on solutions or suspensions of alkali or neutral tungstates.
  3. By fusing a tungstate with sulphur.
The compounds are generally yellow to yellowish brown in colour and yield well-defined crystals which are soluble in water. The solution, on addition of an acid, deposits tungsten trisulphide.

Potassium rnonothiotungstate, K2WO3S.H2O, is the only salt of this type which has been isolated. It is produced by passing hydrogen sulphide into a concentrated solution of potassium tungstate until a slight yellow precipitate is formed. A large bulk of alcohol is then added, and colourless deliquescent crystals are deposited. The salt is soluble in water, and the solution gives a white precipitate with zinc sulphate.

Ammonium dithiotungstate, (NH4)2WO2S2, is obtained as yellow crystals when hydrogen sulphide is passed into a strong ammoniacal solution of ammonium tungstate. The crystals are triclinic pinacoids, with axial ratio a:b:c = 0.703:1:0.3392. The salt is stable when dry, but decomposes when moist.

Potassium dithiotungstate, K2WO2S2, is formed by fusing together potassium tungstate and sulphur in absence of air and extracting with water. It yields lemon-yellow rectangular crystals, which lose water on heating, and if out of contact with air, melt without decomposition.

Potassium trithiotungstate, K2WOS3.H2O, is obtained in quadratic plates by the prolonged action of hydrogen sulphide on potassium tungstate. It is very soluble in water, but may be precipitated by means of alcohol. The crystals deliquesce in a damp atmosphere and effloresce in a dry one. The solution gives a lemon-yellow precipitate with zinc sulphate.

Normal ammonium thiotungstate, (NH4)2WS4, is prepared by the prolonged action of hydrogen sulphide on a dilute solution of ammonium tungstate. It forms transparent, orange-coloured crystals, rhombic bipyramidal, with axial ratio a:b:c = 0.778:1:0.5675, isomorphous with ammonium thiomolybdate. The salt is stable when dry. When heated in an atmosphere of carbon dioxide, tungsten disulphide remains; it is slowly reduced to the metal when heated in hydrogen.

Normal potassium thiotungstate, K2WS4, is prepared in a similar manner to the ammonium salt; or it may be precipitated by adding potassium hydrogen sulphide and alcohol to a solution of the ammonium salt. The crystals are rhombic bipyramids, with axial ratio a:b:c = 0.7495:1:0.5665. It is readily soluble in water. On heating, it melts without decomposition.

The compound, K2WS4.KNO3, is described by Berzelius.

Normal sodium thiotungstate, Na2WS4, is prepared by similar reactions to the above. The crystals are very hygroscopic, and are exceedingly soluble in water. The solutions of normal thiotungstates are not precipitated by zinc sulphate. Sodium thiotungstate is soluble in alcohol.

Thiotungstates of calcium, strontium, and barium have been prepared by the action of hydrogen sulphide on suspensions of the corresponding tungstates, whereby yellow solutions were obtained from which the thiotungstates could be crystallised.

The free acids corresponding to the above salts have not been isolated.


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