Chemical elements
  Vanadium
    Isotopes
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    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

Vanado-vanadates






These salts are made by reducing hot solutions of alkali vanadates with sulphur dioxide; after addition of acetic acid they can be salted out by addition of alkali acetate. The following are known:

(NH4)2O.4VO2.2V2O5.14H2OGreenish-black crystals.
3(NH4)2O.4VO2.4V2O5.6H2OPurple crystals with metallic lustre.
(NH4)2O.2VO2.4V2O5.8H2OGreen crystals.
2K2O.4VO2.V2O5.6H2O.Greenish-black crystals.
5K2O.4VO2.4V2O5.H2OPurple crystals with metallic lustre.
2Na2O.4VO2.V2O5.13H2OBlack, shining, hexagonal prisms.


In addition to the above, several vanado-vanadates have been prepared by fusing alkali carbonates, borates, phosphates, silicates, arsenates, etc., with vanadium pentoxide in air. The fused mass evolves oxygen during cooling, and "spitting" of the material takes place. The phenomenon recalls the behaviour of solidifying silver. On again heating in air, oxygen is re-absorbed and acid vanadates are produced. The evolution of oxygen is accompanied by reduction of a portion of the vanadium pentoxide content with formation of the vanado-vanadate. The reaction is represented:



The oxygen is liberated between the upper limit of stability of the vanado-vanadate and the point of solidification of the fused mass. The proportion of oxygen evolved is independent of the anion with which the metal is combined. The alkali salts can be substituted by thallium compounds but not by alkaline earth oxides. Investigation shows that for each base there is a definite vanadium pentoxide content for which the evolution of oxygen is a maximum. Phase diagrams for the systems V2O5-Na2O, V2O5-K2O, V2O5-Li2O, and V2O5-Tl2O show that in each case three definite compounds are formed, corresponding to the meta-, pyro-, and ortho-vanadates. By the foregoing method the following salts have been prepared: 6Li2O.2VO2.11V2O5; 4Li2O.2VO2.7V2O5; Na2O.2VO2.5V2O5; Na2O.2VO2.4V2O5; Na2O.VO2.2V2O5; 3Na2O.2VO2.5V2O5; K2O.2VO2.8V2O5; K2O. 2VO2.5V2O5; 2K2O.2VO2.9V2O5; K2O.2VO2.4V2O5; K2O.VO2.2V2O5; Ag2O.2VO2.5V2O5.

Vanado-vanadates can also be obtained by fusing alkali vanadites with metavanadates, when no oxidation or loss of oxygen takes place. This process has furnished two salts, Na2O.2VO2.V2O5 and K2O. 2VO2.V2O5.


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