Aluminium arsenate
Aluminium arsenate is an inorganic compound with the formula AlAsO4.[1] 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.[2] Anhydrous form is known as an extremely rare, fumarolic mineral alarsite[3] A synthetic hydrate of aluminium arsenate is produced by hydrothermal method. with the formulation, Al2O3.3As2O5.10H2O.[4]
Modification of aluminium orthoarsenate was carried out by heating different samples to different temperatures. Both amorphous and crystalline forms were obtained.[5] The solubility product was determined to be 10−18.06. for Aluminium arsenate of formula AlAsO4.3.5H2O[6]
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.
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Other names
Aluminum arsenate | |
Identifiers | |
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3D model (JSmol) |
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PubChem CID |
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Properties | |
AlAsO4 | |
Molar mass | 165.901 g/mol |
Appearance | white crystals |
Density | 3.25 g/cm3 |
Melting point | 1,000 °C (1,830 °F; 1,270 K) |
insoluble | |
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 | |
References
- Aluminum arsenate at Chemister
- Chemistry of Arsenic, Antimony, and Bismuth, Edited by N. C. Norman. page 131,
- https://www.mindat.org/min-94.html
- 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
- 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