Aluminium arsenate

Last updated
Aluminium arsenate
Names
Other names
Aluminium arsenate
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/Al.AsH3O4/c;2-1(3,4)5/h;(H3,2,3,4,5)/q+3;/p-3
    Key: RCJAOTMBSRLOJZ-UHFFFAOYSA-K
  • (Octahydrate):InChI=1S/Al.AsH3O4.8H2O/c;2-1(3,4)5;;;;;;;;/h;(H3,2,3,4,5);8*1H2/q+3;;;;;;;;;/p-3
    Key: CHNKHEXWDMIYLG-UHFFFAOYSA-K
  • [O-][As](=O)([O-])[O-].[Al+3]
  • (Octahydrate):O.O.O.O.O.O.O.O.O=[As]([O-])([O-])[O-].[Al+3]
Properties
AlAsO4
Molar mass 165.899 g·mol−1
Appearancecolourless crystals
Density 3.25 g/cm3
Melting point 1,000 °C (1,830 °F; 1,270 K)
insoluble
10−18.06 for 2 AlAsO4.7 H2O. [1]
1.596
Structure
hexagonal
Thermochemistry
Std molar
entropy (S⦵298)
145.6 J/mol K
-1431.1 kJ/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Aluminium arsenate is an inorganic compound with the formula AlAsO4. [2] It is most commonly found as an octahydrate. It is a colourless solid that is produced by the reaction between sodium arsenate and a soluble aluminium salt. Aluminium arsenate occurs naturally as the mineral mansfieldite. [3] Anhydrous form is known as an extremely rare, fumarolic mineral alarsite [4] A synthetic hydrate of aluminium arsenate is produced by hydrothermal method. with the formulation Al2O3·3As2O5·10H2O. [5]

Modification of aluminium orthoarsenate was carried out by heating different samples to different temperatures. Both amorphous and crystalline forms were obtained. [6] The solubility product was determined to be 10−18.06 for aluminium arsenate hydrate of formula AlAsO4·3.5H2O. [1] Like gallium arsenate and boron arsenate, it adopts the α-quartz-type structure. The high pressure form has a rutile-type structure in which aluminium and arsenic are six-coordinate.

References

  1. 1 2 Fernando L. Pantuzzo, Luciano R.G. Santos, Virginia S.T. Ciminelli "Solubility-product constant of an amorphous aluminum-arsenate phase (AlAsO4·3.5H2O) at 25 °C" Hydrometallurgy Volumes 2014, 144–145, Pages 63–68. doi : 10.1016/j.hydromet.2014.01.001
  2. ↑ Aluminum arsenate at Chemister
  3. ↑ Chemistry of Arsenic, Antimony, and Bismuth, Edited by N. C. Norman. page 131,
  4. ↑ "Alarsite".
  5. ↑ Katz, Gerald; Kedesdy, Horst (1954). "A new synthetic hydrate of aluminum arsenate" (PDF). American Mineralogist. 39 (11–12)): 1005–1017.
  6. ↑ B. Sharan "A new modification of aluminum ortho-arsenate" Acta Crystallogr. 1959, vol. 12, 948-949. doi : 10.1107/S0365110X59002729
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