Chemical elements
    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
      Intermediate Vanadium Oxides
      Vanadium Pentoxide
      Sodium Stannovanadates
      Double Vanadates
      Heteropoly-Acids with Vanadium
      Pervanadic Acid
      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

Vanadyl Sulphates

By treating hypovanadic oxide, VO2, with sulphuric acid at about 200° C., or by reducing a sulphuric acid solution of vanadium pentoxide, V2O5, with sulphur dioxide, two distinct compounds are obtainable, according to the quantity of sulphuric acid present:
  1. Neutral vanadyl sulphate, VOSO4.
  2. Acid vanadyl sulphate, 2VOSO4.H2SO4.xH2O.

Vanadyl Sulphate, VOSO4

Vanadyl Sulphate, VOSO4, exists in two modifications, insoluble and soluble. The insoluble variety is best obtained by heating any of the acid vanadyl sulphates to 260° C. It is a greyish-green, micro-crystalline powder, which is insoluble both in hot water and in hot dilute acids. It is readily decomposed by alkalis to form brown, hydrated hypovanadic oxide. On being heated at 130° C. in a sealed tube with a little water, it undergoes conversion into the soluble form, which can also be obtained by evaporation of a solution of the hydrate, 2VOSO4.7H2O, to dryness, or by evaporation of a solution of vanadium pentoxide in sulphuric acid in the presence of alcohol. This modification is a blue, amorphous, gummy mass, completely soluble in water, giving a blue solution which becomes green in air and slowly deposits the green oxide, VO2. On being heated in the absence of air it again forms hypovanadic oxide; in the presence of air the pentoxide, V2O5, is produced.

Several blue, crystalline hydrates of vanadyl sulphate have been prepared from hypovanadic oxide, VO2: VOSO4.2H2O; VOSO4. 2½H2O; VOSO4.3H2O; VOSO4.3½H2O; VOSO4.5H2O; VOSO4. 6½H2O; VOSO4.7H2O. The dihydrate, VOSO4.2H2O, has been prepared electrolytically.5 Most of these give a greyish-green monohydrate, VOSO4.H2O, on being heated to 150° C., and all of them undergo dehydration to form insoluble vanadyl sulphate at 260° C. It is doubtful if these are all individual chemical compounds; they may be mixtures of hydrates. They are, however, characterised by their crystalline forms, and in that they can, in several cases, be prepared by different methods.

Acid Vanadyl Sulphates

Acid Vanadyl Sulphates, of general formula 2VOSO4.H2SO4.xH2O, are prepared by reducing solutions of vanadium pentoxide in sulphuric acid of such concentration that there are more than three molecules of sulphuric acid per molecule of vanadium pentoxide.6 Evaporation on the water-bath yields the pentahydrate, 2VOSO4.H2SO4.5H2O, which, on being heated to 200° C., undergoes dehydration and forms the compound 2VOSO4.SO3 or 2VO2.3SO3. By treatment at intermediate temperatures the following hydrates have also been prepared: 2VOSO4. H2SO4.3H2O; 2VOSO4.H2SO4.2H2O; 4VOSO4.2H2SO4.H2O. Gain7 has shown that hypovanadic oxide combines with sulphur trioxide to produce various other complexes all of which are blue, crystalline, fairly stable substances. They have the general formula 4VO2.xSO3.yH2O, in which x varies between 4 and 10.

Double Salts of Vanadyl Sulphate

Two series of double salts of vanadyl sulphate and alkali sulphates are known. The members of the first series have the general formula 2 VOSO4.H2SO4.xH2O, and are obtained by reducing solutions of the alkali metavanadates in sulphuric acid with sulphur dioxide and then adding excess of the particular alkali sulphate desired. They form blue, crystalline compounds which undergo dehydration at 175° C. The following have been prepared: -


Fischer, by the same method, prepared the double sulphates with calcium, magnesium and aluminium sulphates.

The members of the second series possess the general formula VOSO4.R2SO4.xH2O, and thus contain a smaller molecular proportion of vanadyl sulphate than the members of the preceding series, from which they are prepared by the prolonged action of alcohol on neutral solutions. They also yield dark blue, crystalline compounds, which undergo dehydration at 175° C. The following are known: -


The general compositions of these two series of double salts correspond to the compositions of the double sulphates of divalent metals, e.g. 2ZnSO4.K2SO4 and ZnSO4.K2SO4.6H2O.
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