Names | |
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Other names Aluminium arsenate | |
Identifiers | |
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3D model (JSmol) |
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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). |
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.