Sodium arsenates orthoarsenate

Arsenates are oxidizing agents and are reduced by concentrated hydrochloric acid or sulfur dioxide. Treatment of a solution of orthoarsenate with silver nitrate in neutral solution results in the formation of a chocolate-brown precipitate of silver orthoarsenate, Ag AsO, which may be used as a test to distinguish arsenates from phosphates. With hydrofluoric acid, orthoarsenate solutions yield hexafluoroarsenates, eg, potassium hexafluoroarsenate [17029-22-0] (KAsFg)2 H2O. Arsenates of calcium or lead are used as insecticides sodium arsenate is used in printing inks and as a mordant. 

Sodium orthoarsenate is also obtained electrolytically by the method described under calcium arsenate (p. 198). Yields up to 100 per cent, may be obtained 9 by employing a cell with a diaphragm between iron electrodes. The anolyte should contain sodium arsenite, or sodium hydroxide and arsenious oxide (equivalent to 150 g. As2Os per litre), and the catholyte sodium hydroxide (150 g. per litre). With a current density of 3 amps, per sq. dm. the current efficiency is 100 per cent. A solid crust of sodium arsenate forms around the anode. The process may be rendered continuous by circulating the anolyte and removing the precipitated arsenate. Iron or nickel electrodes are... 

A basic arsenate of composition 3Sr3(As04)2.Sr(0H)2 has been obtained3 as a fine flaky precipitate by the action of sodium hydroxide and strontia-water on an acidified solution of sodium monohydrogen orthoarsenate, care being taken to ensure the absence of carbonate. 

TJranyl Monohydrogen Orthoarsenate, U02HAs04.4H20, is obtained 5 as a pale yellow powder by the addition of uranyl acetate to a solution of arsenic acid or sodium arsenate. It is insoluble in water and acetic acid. 

Zirconium Arsenates.—Zirconium Orthoarsenate, Zr3(As04)4. 5H20, has been obtained 5 as a voluminous white precipitate by adding sodium monohydrogen orthoarsenate to a solution of zireonyl fluoride in hydrochloric acid. Zirconium monohydrogen orthoarsenate, Zr(HAs04)2, appears to be formed slowly by adsorption of arsenic acid by zirconium dioxide.6... 

SYNS MONOSODIUM arsenate SODIUM ARSENATE SODIU.M DIHYDROGEN ARSENATE SODIUM DIHYDROGEN ORTHOARSENATE... 

SYNS FATSCO ant poison sodium ARSENATE (DOT) SODIUM MET. ARSENATE SODIUM ORTHOARSENATE SWEENEY S ANT-GO... 

SODIUM DIHYDROGEN ARSENATE see ARD600 SODIUM DIHYDROGEN ORTHOARSENATE see ARD600... 

Crystals of sodium meta-arsenate-phosphates with P/As ratios of 1, 2, 3, and 4 are prepared by the following procedure (57,60). A mixture of calculated amounts of sodium dihydrogen orthophosphate and sodium dihydrogen orthoarsenate is melted at 620°C. and tempered at 470°C. for 24 hr. The resulting product is hard, needle-shaped crystals. When a mixture of the phosphate and the arsenate with a P/As ratio of 5 is treated by a similar procedure, needle-shaped crystals with considerable amounts of sodium trimetaphosphate are produced. 

Synonyms Arsenic acid, disodium salt Disodium arsenic acid Disodium hydrogen arsenate Disodium hydrogen orthoarsenate Disodium monohydrogen arsenate Sodium acid arsenate Sodium arsenate Sodium arsenate, dibasic Sodium arsenate dibasic, anhydrous Empirical HAsNa204 Formula Na2HAs04... 

Sodium orthoarsenate. See Sodium arsenate Sodium oxalate... 

Aluminium Arsenates.—The orthoarsenate, A1As04, is obtained 2 in the form of elongated lens-shaped crystals when normal sodium orthoarsenate is heated with an excess of aluminium sulphate in a sealed tube at 220° C. The crystals are hexagonal in structure, with a0 = 5-030 and c0 = 5-612 A. the form is similar to that of quartz.3... 

Cadmium Arsenates.—The hydrated normal cadmium orthoarsenate, 2Cd3(As04)2.3H20, falls as a white voluminous precipitate on adding alkali to a solution of cadmium mono- or di-hydrogen arsenate in hydrochloric acid,4 or on addition of sodium orthoarsenate to a solution of cadmium sulphate.5 On drying at 100° C. the anhydrous salt remains. 

Colloidal cobalt arsenate has been obtained in the form of an opalescent jelly either by mixing in the cold a solution of a cobalt salt of a strong acid with potassium dihydrogen orthoarsenate,8 or by successively treating an aqueous solution of a cobaltous salt with ammonium sulphate, acetic acid and an excess of sodium orthoarsenate.9... 

Gold Arsenate is precipitated as a yellowish-white powder when sodium orthoarsenate is added to a hot solution of auric chloride.12... 

Hydroxylamine Orthoarsenate, (NH2OH)3.H3As04, is obtained13 when aqueous arsenic acid is made alkaline with an excess of sodium carbonate and then treated with hydroxylamine hydrochloride until faintly acid. Microscopic rhombic prisms slowly form, which yield an acid solution in hot water, from which they may be recrystallised. The salt readily reduces ammoniacal silver nitrate and Fehling s solution. 

Manganese Arsenates.—Manganous Orthoarsenate, Mns(As04)a. H20, is obtained as brown needles 8 when manganese sulphate is heated with sodium orthoarsenate in a sealed tube at 175° C. 

Mercuric Orthoarsenate, Hg8(As04)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.4 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. 

Basic mercuric sulphate is converted into mercuric orthoarsenate and mercuric oxide by warming with sodium mono hydrogen arsenate solution. Hot acetic acid will extract the oxide.5... 

Palladium Arsenate was reported by Berzelius3 as a pale yellow precipitate formed when sodium orthoarsenate was added to a neutral solution of palladious nitrate. 

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