Chemical elements
  Arsenic
      Occurrence
      Ubiquity
      History
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    Chemical Properties
      Aluminium Arsenide
      Antimony Arsenides
      Barium Arsenide
      Bismuth Arsenides
      Cadmium Arsenides
      Calcium Arsenide
      Cerium Arsenide
      Chromium Arsenides
      Cobalt Arsenides
      Copper Arsenides
      Gold Arsenides
      Iridium Arsenide
      Iron Arsenides
      Lead Arsenides
      Lithium Arsenide
      Magnesium Arsenide
      Manganese Arsenides
      Mercury Arsenides
      Molybdenum Arsenide
      Nickel Arsenides
      Niobium Arsenide
      Palladium Di-arsenide
      Platinum Arsenides
      Potassium Arsenides
      Rhodium Arsenide
      Ruthenium Arsenide
      Silver Arsenides
      Sodium Arsenide
      Strontium Arsenide
      Thallium Arsenide
      Tin Arsenides
      Tungsten Arsenide
      Uranium Arsenide
      Zinc Arsenides
      Arsenic Subhydride
      Arsenic Monohydride
      Arsenic Trihydride
      Arsenic Trifluoride
      Arsenic Pentafluoride
      Arsenic Nitrosyl Hexafluoride
      Arsenic Trichloride
      Arsenic Oxychloride
      Arsenic Pentachloride
      Arsenic Tribromide
      Arsenic Oxybromide
      Arsenic Moniodide
      Arsenic Diiodide
      Arsenic Triiodide
      Arsenic Pentiodide
      Arsenic Suboxide
      Arsenious Oxide
      Aluminium Arsenite
      Ammonium Arsenites
      Antimony Arsenite
      Barium Arsenites
      Beryllium Arsenite
      Bismuth Arsenite
      Cadmium Arsenites
      Calcium Arsenites
      Chromic Arsenite
      Cobalt Arsenites
      Copper Arsenites
      Gold Arsenites
      Iron Arsenites
      Lead Arsenites
      Lithium Arsenite
      Magnesium Arsenites
      Manganese Arsenites
      Mercury Arsenites
      Nickel Arsenites
      Palladium Pyroarsenite
      Platinum Arsenites
      Potassium Arsenites
      Arsenites of Rare Earth Metals
      Rubidium Metarsenite
      Silver Arsenites
      Sodium Arsenites
      Strontium Arsenites
      Thallous Orthoarsenite
      Tin Arsenites
      Titanyl Tetrarsenite
      Tungsto-arsenites
      Uranyl Metarsenite
      Zinc Arsenites
      Zirconium Arsenite
      Arsenic Tetroxide
      Arsenic Pentoxide
      Aluminium Arsenates
      Ammonium Arsenates
      Barium Arsenates
      Beryllium Arsenates
      Bismuth Arsenates
      Cadmium Arsenates
      Caesium Arsenate
      Calcium Arsenates
      Chromium Arsenates
      Cobalt Arsenates
      Copper Arsenates
      Hydroxylamine Orthoarsenate
      Iron Arsenates
      Lead Arsenates
      Lithium Arsenates
      Magnesium Arsenates
      Manganese Arsenates
      Mercury Arsenates
      Molybdenum Arsenates
      Nickel Arsenates
      Palladium Arsenate
      Platinic Arsenate
      Potassium Arsenates
      Rare Earth Metals Arsenates
      Rhodium Arsenate
      Rubidium Arsenates
      Silver Arsenates
      Sodium Arsenates
      Strontium Arsenates
      Thallium Arsenates
      Thorium Arsenates
      Tin Arsenates
      Titanyl Arsenate
      Tungsto-arsenic Acids
      Uranium Arsenates
      Vanado-arsenates
      Zinc Arsenates
      Zirconium Arsenates
      Perarsenates
      Arsenic and Sulphur
      Arsenic Subsulphide
      Tetrarsenic Trisulphide
      Arsenic Disulphide
      Arsenic Trisulphide
      Arsenic Pentasulphide
      Thioarsenates
      Ammonium Thioarsenates
      Antimony Thioarsenate
      Barium Thioarsenates
      Beryllium Thioarsenate
      Bismuth Thioarsenate
      Cadmium Thioarsenates
      Calcium Thioarsenates
      Cerium Thioarsenates
      Chromium Thioarsenate
      Cobalt Thioarsenate
      Copper Thioarsenates
      Gold Thioarsenates
      Iron Thioarsenates
      Lead Thioarsenates
      Lithium Thioarsenates
      Magnesium Thioarsenates
      Manganese Thioarsenates
      Mercury Thioarsenates
      Molybdenum Thioarsenates
      Nickel Thioarsenates
      Platinic Thioarsenate
      Potassium Thioarsenates
      Silver Thioarsenates
      Sodium Thioarsenates
      Strontium Thioarsenates
      Thallium Orthothioarsenate
      Tin Thioarsenates
      Uranyl Thioarsenate
      Yttrium Thioarsenate
      Zinc Thioarsenates
      Zirconium Thioarsenate
      Trioxythioarsenic Acid
      Dioxydithioarsenic Acid
      Oxytrithioarsenic Acid
      Arsenic Monosulphatotrioxide
      Arsenic Disulphatotrioxide
      Arsenic Trisulphatotrioxide
      Arsenic Tetrasulphatotrioxide
      Arsenic Hexasulphatotrioxide
      Arsenic Octasulphatotrioxide
      Complex salts of Sulphato-compounds of Arsenic
      Arsenic Nitride
      Arsenic Imide
      Arsenic Amide
      Arsenic Phosphides
      Arsenic oxyphosphides
      Arsenic Phosphate
      Arsenic Thiophosphate
      Arsenic Tricarbide
      Arsenic Pentasilicide
      Boron Arsenate
    Detection of Arsenic
    Estimation of Arsenic
    Physiological Properties
    PDB 1b92-1ihu
    PDB 1ii0-1tnd
    PDB 1tql-2hmh
    PDB 2hx2-2xnq
    PDB 2xod-3htw
    PDB 3hzf-3od5
    PDB 3ouu-9nse

Vanado-arsenates






These compounds are analogous to the molybdo- and tungsto-arsenates. They are derived from the hypothetical arseno-acid H7[AsO6]. The salts which have hitherto been prepared are all of low vanadium pentoxide content compared with the amount of arsenic pentoxide present, and correspond therefore to the luteo vanado-phosphates. Three series are known. The first has the general formula 2R''O.V2O5.As2O5.xH2O or , where R'' may be Mg, Zn, Cu or Co. They form yellow crystals which are obtained by the addition of arsenic pentoxide to solutions of the respective vanadates, or by the action of the carbonate of the metal on the free vanado-arsenic acid (see below). Of the second series only the ammonium and potassium salts are known, viz. (NH4)2O.2V2O5.As2O5.5H2O or , and K2O.2V2O5.As2O5.5H2O or . These also give rise to yellow crystals. The third series has the general formula 2R2'O.2V2O5.3As2O5.xH2O, where R2' may be (NH4)2, Ca, Sr, Mg, Zn, Mn, Co, Ni. They result from the action of arsenic pentoxide on solutions of vanadates, and form red crystals which, however, are unstable, and are readily converted by water into compounds of the first series.

The free acid of the first series has been obtained in yellow plates by boiling vanadium pentoxide with a solution of arsenic acid. Its composition is V2O5.As2O5.10H2O or . Recrystallisation of this hydrate from concentrated nitric acid gives a dihydrate, V2O5.As2O5.2H2O, which can be looked upon as the acid . The anhydride, V2O5.As2O5, is obtained by heating the dihydrate to 440° C.


Molybdo-vanadoarsenates

A number of compounds have been described which are analogous to the molybdo-vanadophosphates, and which contain arsenic for the nuclear atom of the complex anion. In many cases these compounds approximate to the general formula , where x + y = 6; x and y are not necessarily whole numbers, because of the tendency shown by these heteropoly-acid salts to form isomorphous mixtures of simple compounds. Ammonium, barium and thallium salts have been prepared.

Tungsto-vanadoarsenates

These are comparable to the molybdo-vanadoarsenates, and can be represented generally as



where x + y = 6, although x and y are not necessarily whole numbers. Canneri found a definite relation to exist between the composition of the salt obtained and that of the solution from which it separates, whence it is inferred that a condition of equilibrium exists between various salts in solution or between their ions; this equilibrium for fixed concentrations is remarkably sensitive to changes in temperature or acidity. Among other salts three series of ammonium salts have been obtained, which approach to the following formulae:

; ; .

Barium and thallium salts have also been described, and some of the free acids have been isolated.

Canneri has succeeded in preparing a large number of mixed crystals of salts, and in some cases of the free acids, which belong to different series; for example, mixed crystals of tungsto-vanadophosphates and tungsto-vanadoarsenates, of tungsto-vanadophosphates and molybdo-vanadophosphates, of tungsto-vanadoar senates and molybdo-vanadoarsenates; and, finally, mixed crystals of members of all the four series mentioned have been obtained. The mixed crystals have the- same crystalline habit as that of their components, and complete isomorphism exists between any two series which mix in all proportions to form continuous series of mixed crystals containing four or five different oxygenated acid radicals. The crystallographic data of a number of ammonium tungsto-vanadoarsenates have also recently been independently determined, and it has been shown that the crystal form is unaffected when the arsenic is substituted by phosphorus, or when the (W2O7)'' radicals are partially substituted by (Mo2O7)''.

Tungsto-vanadoarsenophosphates

Several ammonium salts have been prepared, which are most probably isomorphous mixtures of arsenates and phosphates.

Vanado-tungstomolybdoarsenophosphates

Vanado-tungstomolybdoarsenophosphates have been described; these are also isomorphous mixtures of simpler compounds.
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