Chemical elements
    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
      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
      Zinc Arsenates
      Zirconium Arsenates
      Arsenic and Sulphur
      Arsenic Subsulphide
      Tetrarsenic Trisulphide
      Arsenic Disulphide
      Arsenic Trisulphide
      Arsenic Pentasulphide
      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

Mercury Arsenates

Mercurous Orthoarsenate, Hg3AsO4

Mercurous Orthoarsenate, Hg3AsO4, is formed as an orange-yellow precipitate when a cold solution of mercurous nitrate is added to a large excess of aqueous sodium monohydrogen orthoarsenate. If the mercury salt is in excess, the basic double salt, 3Hg3AsO4.2(HgNO3.Hg2O), separates which, when freshly precipitated and washed, is converted to the normal arsenate by treatment with aqueous sodium monohydrogen orthoarsenate. The double salt is white and soluble in hydrochloric acid. The normal arsenate may also be obtained by prolonged heating at 230° C. of a mixture of mercury and arsenic acid solution (containing 12.5 per cent. As2O5) in a sealed tube.

Mercurous orthoarsenate yields orange rhombic prisms which are insoluble in water. Hydrochloric acid converts it into calomel and arsenic acid.

Mercurous Monohydrogen Orthoarsenate, Hg2HAsO4

Mercurous Monohydrogen Orthoarsenate, Hg2HAsO4H2O, is formed when a concentrated solution of arsenic acid is treated with a solution of mercurous nitrate until the precipitate no longer redissolves. The product is white, but becomes red when dried. On further heating it loses water of crystallisation and at a higher temperature yields mercury and mercuric arsenate, the latter also decomposing at a still higher temperature to yield arsenious oxide, oxygen and mercury. The salt dissolves in cold nitric acid and may be reprecipitated by ammonia. Boiling nitric acid and cold concentrated hydrochloric acid decompose it.

Orange-red crystals of dimercurous silver arsenate, Hg2AgAsO4, have been obtained by adding hydrogen peroxide solution, free from chlorides, to a solution of silver nitrate, mercurous nitrate and potassium arsenite in dilute nitric acid. The crystals are blackened by ammonium hydroxide solution owing to liberation of metallic mercury.

Mercurous Metarsenate, HgNaO3

Mercurous Metarsenate, HgNaO3, has been obtained by prolonged heating in a sealed tube at 150° C. of a mixture of mercury and aqueous arsenic acid, the latter of 50 to 75 per cent, concentration, and by boiling a mixture of mercuric oxide and aqueous arsenic acid until dry, thoroughly washing the residue with water and drying at 100° C. It yields pale yellow hexagonal plates with axial ratio a:c = 1:1.5096. The crystals blacken superficially in light. The salt decomposes on heating. It is insoluble in water, alcohol and acetic acid. It dissolves in dilute nitric acid and the addition of ammonia to the solution precipitates mercurous monohydrogen orthoarsenate.

Mercuric Orthoarsenate, Hg3(AsO4)2

Mercuric Orthoarsenate, Hg3(AsO4)2, is obtained by precipitating a solution of mercuric nitrate with a solution of sodium mono- or dihydrogen arsenate, or by dropping aqueous arsenic acid into excess of mercuric nitrate solution. It is a heavy citron-yellow powder. Hot water dissolves it slightly without decomposition, and shining crystals may separate from the cooled solution. Hydrochloric acid dissolves it freely, nitric acid less readily, and arsenic acid not at all. Brine solution converts it into red-brown mercury oxychloride. Potassium bromide solution colours it brown, and a yellow residue is ultimately left. Potassium iodide forms mercuric iodide.

Sodium dihydrogen arsenate or arsenic acid does not precipitate mercuric chloride solution, but the latter reacts with normal silver arsenate to form normal mercuric arsenate and silver chloride. Yellow precipitates containing normal mercuric arsenate, mercuric chloride and mercuric oxide are thrown down from mercuric chloride solution by a solution of sodium monohydrogen arsenate.

Basic mercuric sulphate is converted into mercuric orthoarsenate and mercuric oxide by warming with sodium monohydrogen arsenate solution. Hot acetic acid will extract the oxide.

When mercuric oxide is treated with aqueous arsenic acid, the solid phase separates into two layers, one of which is mercuric oxide and the other a basic mercuric arsenate of composition 3HgO.Hg3(AsO4)2. When ammonium arsenate solution acts on mercuric oxide, a product of composition Hg2NH2AsO4 is obtained.

Complex pyroarsenates

Complex pyroarsenates of composition HgSrAs2O7 and HgBaAs2O7.H2O have been prepared.

A double salt of composition Hg3AsO4.2HgNO3.2H2O has been described as separating in warty masses or needle-shaped crystals when a solution of mercurous monohydrogen orthoarsenate in concentrated nitric acid is diluted with its own volume of water and then treated with aqueous ammonia and allowed to stand for a time.

Colloidal mercuric orthoarsenate

Colloidal mercuric orthoarsenate has been prepared by adding mercuric chloride to a 10 per cent, solution of sodium protalbinate, dissolving the precipitate formed in aqueous sodium hydroxide and treating the latter solution with sodium monohydrogen arsenate. After dialysis, the solution is evaporated to dryness under reduced pressure, when an olive-green residue is obtained. This dissolves readily in water to give a colloidal solution which is olive-green in transmitted light and grey in reflected light.
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