Aluminium arsenate
Chemical compound
From Wikipedia, the free encyclopedia
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]
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| Other names
Aluminium arsenate | |
| Identifiers | |
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3D model (JSmol) |
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| ChemSpider | |
PubChem CID |
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CompTox Dashboard (EPA) |
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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 2 AlAsO4.7 H2O.[1] |
Refractive index (nD) |
1.596 |
| Structure | |
| hexagonal | |
| Thermochemistry | |
Std molar entropy (S⦵298) |
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).
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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.