Chemical elements
  Vanadium
    Isotopes
    Energy
    Preparation
    Applications
    Physical Properties
    Chemical Properties
      Hypovanadous Oxide
      Vanadous Oxide
      Hypovanadic Oxide
      Vanadic Oxide
      Hypovanadous Fluoride
      Vanadous Fluoride
      Vanadium Tetrafluoride
      Vanadium Pentafluoride
      Vanadyl Difluoride
      Vanadium Oxytrifluoride
      Vanadium Dioxyfluoride
      Hypovanadous Chloride
      Vanadous Chloride
      Hypovanadic Chloride
      Divanadyl Chloride
      Vanadium Oxymonochloride
      Vanadyl Dichloride
      Vanadium Oxytrichloride
      Vanadium Oxydichloride
      Vanadous Bromide
      Hypovanadic Bromide
      Vanadium Oxymonobromide
      Vanadyl Dibromide
      Vanadium Oxytribromide
      Hydrated Vanadium Tri-iodide
      Vanadium Suboxide
      Hypovanadous Oxide
      Vanadous Oxide
      Hypovanadic Oxide
      Hypovanadates
      Intermediate Vanadium Oxides
      Vanado-vanadates
      Vanadium Pentoxide
      Orthovanadates
      Sodium Stannovanadates
      Vanadates
      Pyrovanadates
      Metavanadates
      Polyvanadates
      Double Vanadates
      Heteropoly-Acids with Vanadium
      Vanado-phosphates
      Molybdo-vanadophosphates
      Vanado-arsenates
      Molybdo-vanadoarsenates
      Tungsto-vanadoarsenates
      Molybdo-vanadates
      Tungsto-vanadates
      Uranyl-vanadates
      Molybdo-vanadosilicates
      Tungsto-vanadosilicates
      Vanado-selenites
      Vanado-tellurites
      Vanado-iodates
      Vanado-periodates
      Oxalo-vanadates
      Pervanadic Acid
      Pyropervanadates
      Orthopervanadates
      Vanadium Monosulphide
      Vanadium Trisulphide
      Vanadium Pentasulphide
      Vanadium Oxysulphides
      Hypovanadous Sulphate
      Vanadous Sulphate
      Vanadyl Sulphites
      Vanadyl Sulphates
      Vanadic Sulphates
      Vanadyl Dithionate
      Ammonium Orthothiovanadate
      Ammonium Pyroxyhexathiovanadate
      Sodium Orthoxytrithiovanadate
      Sodium Orthoxymonothiovanadate
      Vanadium Selenides
      Vanadyl Selenite
      Vanadyl Selenates
      Vanadium Subnitride
      Vanadium Mononitride
      Vanadium Dinitride
      Alkali Vanadyl Nitrites
      Vanadium Nitrates
      Vanadyl Hypophosphite
      Vanadyl Phosphates
      Vanadous Pyrophosphate
      Vanadyl Arsenates
      Vanadium Carbide
      Vanadyl Cyanide
      Potassium Vanadocyanide
      Potassium Vanadicyanide
      Vanadium Ferrocyanides
      Ammonium Vanadyl Thiocyanate
      Vanadium Subsilicide
      Vanadium Disilicide
      Vanadium Boride
    Detection, Estimation
    PDB 1b8j-2i4e
    PDB 2jhr-6rsa

Hypovanadates






Hypovanadates also known as Vanadites. In addition to being soluble in acids, hypovanadic oxide dissolves in excess of hot alkalis. Cooling these solutions in the absence of air gives rise to a series of crystalline hypovanadates or vanadites. Insoluble vanadites are formed by double decomposition of a metallic salt and an alkali vanadite; they usually possess the general formula R2V4O9. xH2O, and are perhaps salts of the hypothetical acid H2V4O9. They are comparable to the salts produced by other weakly acid oxides, e.g. uranates, metatungstates and borates, in that the acid oxide has undergone condensation to a poly-acid.

Vanadites are either black or brown in the solid state. They become green in damp air, and in solution readily undergo oxidation to the corresponding vanadates. Addition of tannin solution produces a blue-black coloration. Lead acetate throws down a curdy, brown precipitate; silver nitrate gives a black, crystalline precipitate. According to Crow the latter has the composition of a silver vanadite, in which there are, however, only two molecules of acid oxide in combination with one molecule of the base, Ag2O.2VO2; but according to Koppel and Goldmann the precipitate consists of a mixture of silver vanadate, silver vanadite, and metallic silver. The following vanadites have been prepared:


Ammonium Vanadite, (NH4)2V4O9,3H2O

A solution of a vanadyl salt, e.g. vanadyl dichloride, VOCl2, is slowly added in calculated quantity to boiling concentrated ammonia solution. On cooling in the absence of air, golden-brown, glistening needles or scales are deposited, readily soluble in water but insoluble in alcohol, ether, or ammonia. The substance gradually loses ammonia on exposure to air.

Barium Vanadite, BaV4O9,4-5H2O

Barium Vanadite forms two hydrates, BaV4O9.4H2O and BaV4O9.5H2O, which are obtained by the action of excess of baryta water on a solution of vanadyl dichloride. They are brown, amorphous substances, easily soluble in nitric and hydrochloric acids.

Lead Vanadite, PbV2O5

Lead Vanadite, PbV2O5 or PbO.2VO2, is obtained as a brown, curdy precipitate by the action of lead acetate on potassium vanadite.

Potassium Vanadite, K2V4O9,4H2O

A boiling solution of a vanadyl salt is poured into an excess of a 10 per cent, solution of caustic potash and the product cooled in the absence of air. Alternatively, a solution of ammonium vanadite is warmed with caustic potash. Potassium vanadite forms a brown, pearly, glistening mass, and is similar to the ammonium salt in its general properties. A heptahydrate, K2V4O9.7H2O, has been reported.

Sodium Vanadite, Na2V4O9,4H2O

Sodium Vanadite, Na2V4O9.4H2O, forms golden-brown needles, and is prepared similarly to the corresponding potassium salt. Brown, crystalline scales of a heptahydrate, Na2V4O9.7H2O, have also been reported.
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