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

Vanado-selenites






Three series of alkali vanado-selenites are known, the members of which are all prepared by treating solutions of alkali vanadates with selenous acid in varying proportions, or by acidifying mixed solutions of vanadates and selenites with acetic acid. The members of the first series are yellow, and have the composition R2O.V2O5.2SeO2.xH2O. The second series of salts is orange, and includes types of varying composition: R2O.3V2O5.4SeO2.xH2O, R2O.6V2O5.8SeO2.xH2O, as well as other types which contain greater proportions of SeO2. The salts belonging to the third series are red, and have the composition 4R2O.6V2O5.5SeO2.xH2O. All these vanado-selenites lose selenous oxide on being boiled with water. It has been shown that when the same amount of ammonium metavanadate is boiled with selenous acid solutions of gradually increasing concentration, the yellow crystals obtained contain gradually increasing proportions of selenous oxide. It appears, therefore, that the large number of vanado-selenites known, and their complexity, are due to their semi-colloidal character, in consequence of which they adsorb constituents from solutions. As might be expected, only a few of them can be represented by co-ordinative formulae. According to Prandtl, the second and third series above are derivatives of hexavanadic acid, H4V6O17.

By the action of vanadium pentoxide on selenous acid solutions, or by reduction of a solution of vanadium pentoxide in selenic acid, red crystals of a free vanado-selenous acid have been obtained, the composition of which is 3V2O5.4SeO2.4H2O.xaq. It contains four molecules of water of constitution, and, according to Prandtl, should be formulated H4V6O17.4H2SeO3.(x – 2)aq.


© Copyright 2008-2012 by atomistry.com