Chemical elements
  Arsenic
      Occurrence
      Ubiquity
      History
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    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

Calcium Arsenites






The ternary system CaO-As2O3-H2O, investigated at 0°, 25° and 99° C. by the method indicated under barium arsenites, gives evidence of the formation of two arsenites,

Ca(OH)AsO2 or CaHNaO3, which may be considered to be either a basic metarsenite or calcium hydrogen orthoarsenite, and Ca(AsO2)2, calcium metarsenite. When mixtures of arsenious oxide and quicklime are heated, reaction commences at about 300° C. and at 465° C. considerable heat is evolved and calcium orthoarsenite, Ca3(NaO3)2, is formed. An industrial process for the manufacture of this compound consists in treating a dry mixture of quicklime (3 moles) and arsenious oxide (1 mole) with dry steam. It may also be obtained by precipitation of dilute calcium chloride solution with potassium orthoarsenite, or of lime-water with boiling aqueous arsenious acid. It is a white amorphous powder, which may be dried at 100° C. It is only slightly soluble in water, but dissolves in acids. At red heat it decomposes with volatilisation of arsenic, leaving calcium arsenate. The latter is also formed when the arsenite is heated in oxygen. Calcium dihydrogen arsenile, Ca(H2NaO3)2.aq., is formed when excess of lime-water is added to an ammoniacal solution of arsenious oxide, or when lime-water, or a solution of calcium chloride, is added to aqueous ammonium metarsenite, keeping the latter in excess. It is obtained as a white powder or as a gelatinous mass, and contains 5 to 11H2O. It is fairly soluble in water, the solution having an alkaline reaction. It is insoluble in absolute alcohol. Calcium monohydrogen arsenite is mentioned above.


Calcium Pyroarsenite, Ca2As2O5

Calcium Pyroarsenite, Ca2As2O5, is a white powder obtained by slowly precipitating a solution of arsenious acid with excess of lime-water, or by adding calcium chloride or sulphate to aqueous ammonium arsenite, and heating the precipitate to 105° C. If the product is dried in the air at the ordinary temperature, the monohydrate is obtained. At red heat calcium arsenate is formed. The pyroarsenite is only slightly soluble in water, 100 parts dissolving 0.025 to 0.030 part of the salt. It is more soluble in the presence of alkali chlorides and some ammonium salts, such as the nitrate, sulphate, acetate and succinate. It also dissolves in dilute acids.

Calcium Metarsenite, Ca(AsO2)2

Calcium Metarsenite, Ca(AsO2)2, is an amorphous white powder, anhydrous at 100° C., obtained by precipitation of calcium chloride with ammonium arsenite in ammoniacal solution. It is also produced as a commercial preparation by the interaction of milk of lime and arsenious oxide with vigorous stirring at 100° C., or by heating together at 60° to 70° C. arsenious oxide and slaked lime. This product is somewhat impure, containing calcium arsenate and a trace of free lime. Its solubility in water at 15° C. is about 0.04 to 0.05 per cent. When strongly heated in an inert gas it decomposes, forming calcium and arsenious oxides and a little arsenic.

A salt of composition Ca3As4O9.3H2O, which may be regarded as consisting of 1 molecule of pyro-combined with 1 molecule of metarsenite, Ca2As2O5.Ca(AsO2)2, or as a derivative of a hypothetical tetrarsenious acid derived thus -

2As2O3 + 3H2O = H6As4O9

has been prepared by adding a solution of the corresponding potassium salt to a concentrated solution of calcium chloride. The white precipitate, after washing with alcohol, may be dried in the air. At 100° C. it loses 1 molecule of water. It is somewhat soluble in water.
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