Sodium arsenate

Names
	IUPAC name Sodium dihydrogen arsenate
	Other names sodium arsenate
Identifiers
CAS Number	(anhydrous): 13464-38-5 ; (dodecahydrate): 13510-46-8; 7631-89-2;
3D model (JSmol)	(anhydrous): Interactive image; (heptahydrate): Interactive image; (dodecahydrate): Interactive image;
ChEBI	(anhydrous): CHEBI:84070 ;
ChemSpider	(anhydrous): 43027; (dodecahydrate): 29325835;
ECHA InfoCard	100.033.334
EC Number	(anhydrous): 236-682-3;
PubChem CID	(anhydrous): 47275; (heptahydrate): 23622126; (dodecahydrate): 57348098;
UNII	(anhydrous): 7XO134LHLN;
CompTox Dashboard (EPA)	(anhydrous): DTXSID9039367; (dodecahydrate): DTXSID20721563;
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Properties
Chemical formula	H24Na3AsO16 (dodecahydrate)
Molar mass	207.88851 g/mol
Appearance	colourless solid
Density	1.517 g/cm3 (dodecahydrate)
Solubility in water	soluble
Hazards
Main hazards	toxic
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H301, H331, H350, H410
GHS precautionary statements	P201, P202, P261, P264, P270, P271, P273, P281, P301+310, P304+340, P308+313, P311, P321, P330, P391, P403+233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	(what is ?)
	Infobox references

Sodium arsenate is the inorganic compound with the formula Na₃AsO₄. Related salts are also called sodium arsenate, including Na₂HAsO₄ (disodium hydrogen arsenate) and NaH₂AsO₄ (sodium dihydrogen arsenate). The trisodium salt is a white or colourless solid that is highly toxic. It is usually handled as the dodecahydrate Na₃AsO₄^.12H₂O.^[1]

The compound can be obtained by neutralizing arsenic acid:

H₃AsO₄ + 3 NaOH → Na₃AsO₄ + 3 H₂O

The salt (as its dodecahydrate) is isomorphous with trisodium phosphate.^[2] The anion AsO₄^3- exists at high pH, but below pH 11.5, it converts to HAsO₄^2- (also written HOAsO₃^2-).

References[]

^ Grund, S. C.; Hanusch, K.; Wolf, H. U. "Arsenic and Arsenic Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_113.pub2.CS1 maint: multiple names: authors list (link)
^ Remy, Francis; Guerin, Henri "Radiocrystallographic study of dodecahydrate trisodium arsenate and vanadate Na3AsO4.12H2O and Na3VO4.12H2O, and some hydrates of fluorinated or hydroxylated salts of general formula: M3XO4.xMY.(10 - x)H2O where M = Na, K; X = P, As, V and Y = F, OH" Bulletin de la Société Chimique de France 1970, vol. 6, pp. 2073-8.

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[Ullmann-1] Grund, S. C.; Hanusch, K.; Wolf, H. U. "Arsenic and Arsenic Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_113.pub2.CS1 maint: multiple names: authors list (link)

[2] Remy, Francis; Guerin, Henri "Radiocrystallographic study of dodecahydrate trisodium arsenate and vanadate Na3AsO4.12H2O and Na3VO4.12H2O, and some hydrates of fluorinated or hydroxylated salts of general formula: M3XO4.xMY.(10 - x)H2O where M = Na, K; X = P, As, V and Y = F, OH" Bulletin de la Société Chimique de France 1970, vol. 6, pp. 2073-8.

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