Chemistry:Aluminium arsenate
| Names | |
|---|---|
| Other names
Aluminium arsenate
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| Identifiers | |
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3D model (JSmol)
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PubChem CID
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| Properties | |
| AlAsO4 | |
| Molar mass | 165.899 g·mol−1 |
| Appearance | colourless crystals |
| Density | 3.25 g/cm3 |
| Melting point | 1,000 °C (1,830 °F; 1,270 K) |
| insoluble | |
Solubility product (Ksp)
|
10−18.06 for [math]\ce{ 2 AlAsO4.7 H2O }[/math].[1] |
Refractive index (nD)
|
1.596 |
| Structure | |
| hexagonal | |
| Thermochemistry | |
Std molar
entropy (S |
145.6 J/mol K |
Std enthalpy of
formation (ΔfH⦵298) |
-1431.1 kJ/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Aluminium arsenate is an inorganic compound with the formula AlAsO
4.[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 Al
2O
3 · 3As
2O
5 · 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 AlAsO
4 · 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
- ↑ 1.0 1.1 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
- ↑ Aluminum arsenate at Chemister
- ↑ Chemistry of Arsenic, Antimony, and Bismuth, Edited by N. C. Norman. page 131,
- ↑ "Alarsite". https://www.mindat.org/min-94.html.
- ↑ Katz, Gerald; Kedesdy, Horst (1954). "A new synthetic hydrate of aluminum arsenate". American Mineralogist 39 (11–12)): 1005–1017. http://www.minsocam.org/ammin/AM39/AM39_1005.pdf.
- ↑ B. Sharan "A new modification of aluminum ortho-arsenate" Acta Crystallogr. 1959, vol. 12, 948-949. doi:10.1107/S0365110X59002729
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