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.^[2]

Sodium arsenate

Names
IUPAC name Trisodium arsorate[1]
Other names sodium arsenate
Identifiers
CAS Number	(anhydrous): 13464-38-5 N (dodecahydrate): 13510-46-8 7631-89-2
3D model (JSmol)	(anhydrous): Interactive image (heptahydrate): Interactive image (dodecahydrate): Interactive image
ChEBI	(anhydrous): CHEBI:84070 Y
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
InChI (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
SMILES (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
Chemical formula	H24Na3AsO16 (dodecahydrate)
Molar mass	207.88851 g/mol
Appearance	colourless solid
Density	1.517 g/cm3 (dodecahydrate)
Solubility in water	soluble
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	toxic
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H331, H350, H410
Precautionary statements	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). Y verify (what is YN ?) Infobox references

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.^[3] The anion AsO₄^3- exists at high pH, but below pH 11.5, it converts to HAsO₄^2- (also written HOAsO₃^2-).