Sodium arsenate

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]

Sodium arsenate
Na3AsO4.svg
Names
IUPAC name
Sodium dihydrogen arsenate
Other names
sodium arsenate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.033.334 Edit this at Wikidata
EC Number
  • (anhydrous): 236-682-3
UNII
  • (anhydrous): InChI=1S/AsH3O4.3Na/c2-1(3,4)5;;;/h(H3,2,3,4,5);;;/q;3*+1/p-3
    Key: CDBAKLRDFBGJOX-UHFFFAOYSA-K
  • (heptahydrate): InChI=1S/AsH3O4.3Na.7H2O/c2-1(3,4)5;;;;;;;;;;/h(H3,2,3,4,5);;;;7*1H2/q;3*+1;;;;;;;/p-3
    Key: KOPCAWUPVBHZIP-UHFFFAOYSA-K
  • (dodecahydrate): InChI=1S/AsH3O4.3Na.12H2O/c2-1(3,4)5;;;;;;;;;;;;;;;/h(H3,2,3,4,5);;;;12*1H2/q;3*+1;;;;;;;;;;;;/p-3
    Key: UVNGJDIGNLIVPE-UHFFFAOYSA-K
  • (anhydrous): [O-][As](=O)([O-])[O-].[Na+].[Na+].[Na+]
  • (heptahydrate): O.O.O.O.O.O.O.[O-][As](=O)([O-])[O-].[Na+].[Na+].[Na+]
  • (dodecahydrate): O.O.O.O.O.O.O.O.O.O.O.O.[O-][As](=O)([O-])[O-].[Na+].[Na+].[Na+]
Properties
H24Na3AsO16 (dodecahydrate)
Molar mass 207.88851 g/mol
Appearance colourless solid
Density 1.517 g/cm3 (dodecahydrate)
soluble
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
toxic
GHS labelling:
GHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard
Danger
H301, H331, H350, H410
P201, P202, P261, P264, P270, P271, P273, P281, P301+P310, P304+P340, P308+P313, P311, P321, P330, P391, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 AsO43- exists at high pH, but below pH 11.5, it converts to HAsO42- (also written HOAsO32-).

ReferencesEdit

  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.{{cite encyclopedia}}: 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.