Chemical elements
  Molybdenum
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
    Alloys
    Compounds
      Molybdenum Hexafluoride
      Fluoroxypermolybdates
      Molybdenum Dichloride
      Molybdenum Trichloride
      Molybdenum Tetrachloride
      Molybdenum Pentachloride
      Molybdenum Oxychlorides
      Chlormolybdic Acids
      Molybdenum Dibromide
      Molybdenum Tribromide
      Molybdenum Tetrabromide
      Molybdenum Oxybromide
      Molybdenum Di-iodide
      Molybdenum Oxyiodide
      Iodomolybdic Acid
      Molybdenum Sesquioxide
      Molybdenum Dioxide
      Molybdenum Oxide Blue
      Molybdenum Trioxide
      Molybdates
      Aluminium Molybdates
      Ammonium Molybdate
      Ammonium Dimolybdate
      Ammonium Paramolybdate
      Ammonium Trimolybdate
      Ammonium Tetramolybdate
      Ammonium Octamolybdate
      Barium Molybdates
      Barium Paramolybdate
      Barium Trimolybdate
      Barium Tetramolybdate
      Barium Octamolybdate
      Barium Nonamolybdate
      Beryllium Molybdate
      Bismuth Molybdates
      Cadmium Molybdates
      Caesium Molybdates
      Calcium Molybdate
      Calcium Trimolybdate
      Calcium Tetramolybdate
      Calcium Octamolybdate
      Chromium Molybdates
      Cobalt Molybdates
      Cobalt Dimolybdate
      Cobalt Trimolybdate
      Copper Molybdates
      Ferrous Molybdate
      Ferric Molybdate
      Indium Molybdate
      Lead Molybdates
      Lithium Molybdate
      Lithium Dimolybdate
      Lithium Paramolybdate
      Lithium Trimolybdate
      Lithium Tetramolybdate
      Magnesium Molybdates
      Magnesium Paramolybdate
      Magnesium Trimolybdate
      Manganese Molybdate
      Mercurous Molybdates
      Nickel Molybdates
      Potassium Molybdate
      Potassium Dimolybdate
      Potassium Paramolybdate
      Potassium Trimolybdate
      Potassium Tetramolybdate
      Potassium Octamolybdate
      Potassium Decamolybdate
      Rhodium Molybdates
      Rubidium Molybdate
      Rubidium Dimolybdate
      Rubidium Paramolybdate
      Rubidium Trimolybdate
      Rubidium Tetramolybdates
      Silver Molybdates
      Normal Silver Molybdate
      Sodium Molybdate
      Sodium Dimolybdate
      Sodium Paramolybdate
      Sodium Trimolybdate
      Sodium Tetramolybdate
      Sodium Iodomolybdate
      Strontium Molybdate
      Thallous Molybdate
      Thallous Paramolybdate
      Thallous Tetramolybdate
      Thorium Molybdate
      Uranium Molybdates
      Uranyl Octamolybdate
      Zinc Molybdates
      Zinc Trimolybdate
      Zinc Tetramolybdate
      Zinc Octamolybdate
      Zirconium Molybdate
      Permolybdic Acid
      Molybdenum Sesquisulphide
      Molybdenum Disulphide
      Dimolybdenum Pentasulphide
      Molybdenum Trisulphide
      Molybdenum Tetrasulphide
      Thiomolybdates
      Ammonium Thiomolybdates
      Ammonium Molybdosulphites
      Potassium Thiomolybdate
      Potassium Thiodimolybdate
      Potassium Dithiodioxymolybdate
      Potassium Molybdosulphite
      Sodium Thiomolybdates
      Sodium Molybdosulphites
      Molybdenum Sulphates
      Molybdenum Selenide
      Complex Molybdoselenites
      Chromates of Molybdenum
      Molybdenum Phosphide
      Molybdic Metaphosphate
      Heteropoly-compounds with Phosphorus
      12-Molybdophosphoric Acid
      9-Molybdophosphoric Acid
      172-Molybdophosphoric Acid
      Molybdohypophosphates
      Molybdophosphites
      Molybdohypophosphites
      12-Molybdo-arsenates
      9-Molybdo-arsenates
      3-Molybdo-arsenates
      Molybdenum Carbides
      Molybdenum Carbonyl
      Reddish-violet Salts
      Yellow Salts
      Thiocyanates of Molybdenum
      Molybdenum Monosilicide
      Molybdenum Sesquisilicide
      Molybdenum Disilicide
      Molybdosilicic Acid and Molybdosilicates
      12-Molybdosilicic Acid
    PDB 1aa6-1qh8
    PDB 1r27-2jir
    PDB 2min-3unc
    PDB 3uni-4f6t

Molybdenum Sesquioxide, Mo2O3






Molybdenum Sesquioxide, Mo2O3, is obtained by suitable reduction of the dioxide or trioxide, e.g. by magnesium, zinc, or, preferably, zinc coated with cadmium, and sulphuric or hydrochloric acid, and is apparently known only in the hydrated condition. The hydroxide Mo(OH)3, which may also be obtained electrolytically, was first prepared by Berzelius by the action of zinc and a slight excess of hydrochloric acid upon an aqueous solution of an alkali molybdate; a series of colour changes takes place, the colourless liquid becoming blue, then brown, and finally black. On addition of ammonia the hydroxide separates as a brown powder, which may be freed from traces of zinc salts by washing with very dilute hydrochloric acid. Further, the hydrated sesquioxide is obtained by interaction of potash or soda, and molybdenum dichloride or dibromide, hydrogen being simultaneously evolved, whereas a salt of the same oxide is obtained upon reduction of a solution of molybdic acid in hydrochloric acid by means of copper. The reduction of ammonium molybdate by colloidal palladium, if carried out at ordinary temperatures, yields the tetra-hydroxide Mo(OH)4; if, however, the reduction is effected at 50° to 60° C. under a slight pressure, the trihydroxide is obtained as a black sludge:

(NH4)6Mo7O24.4H2O + 21H = 7Mo(OH)3 + 6NH3 + 7H2O.

Molybdenum trihydroxide is an amorphous black substance, becoming reddish brown by slow oxidation in the air. On heating to redness the substance deflagrates, but does not yield the anhydrous oxide. It is insoluble in caustic potash or potassium carbonate solution, but dissolves in excess of ammonium carbonate; its solutions in acids are black in colour.

The salts corresponding to this oxide are dark grey or black, while their solutions have a dark purple or black colour; they are only slightly oxidised in air. The sulphide is an insoluble brown substance, precipitated by hydrogen sulphide or by ammonium sulphide; the chloride, iodide, fluoride, sulphate, and nitrate are soluble. A number of other salts have been prepared.


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