Ammonium aluminium sulfate

Ammonium aluminium sulfate

Names
IUPAC name Aluminium ammonium bis(sulfate)
Other names Ammonium alum Tschermigite
Identifiers
CAS Number	7784-25-0 7784-26-1 (dodecahydrate)
ChemSpider	2297489 56419 (dodecahydrate)
EC Number	232-055-3
Jmol interactive 3D	Image
RTECS number	WS5640010
InChI InChI=1S/Al.H3N.2H2O4S/c;;2*1-5(2,3)4/h;1H3;2*(H2,1,2,3,4)/q+3;;;/p-3 Key: LCQXXBOSCBRNNT-UHFFFAOYSA-K InChI=1/Al.H3N.2H2O4S/c;;2*1-5(2,3)4/h;1H3;2*(H2,1,2,3,4)/q+3;;;/p-3 Key: LCQXXBOSCBRNNT-DFZHHIFOAY
SMILES [Al+3].[O-]S(=O)(=O)[O-].[O-]S([O-])(=O)=O.[NH4+]
Properties[1]
Chemical formula	(NH4)Al(SO4)2
Molar mass	237.15 g/mol (anhydrous) 453.33 g/mol (dodecahydrate)
Appearance	white crystals
Density	2.45 g/cm^3 (anhydrous) 1.64 g/cm^3 (dodecahydrate)
Melting point	93.5 °C (200.3 °F; 366.6 K) (dodecahydrate)
Boiling point	120 °C (248 °F; 393 K) dehydr. (dodecahydrate)
Solubility in water	15 g/100 ml (20 °C, dodecahydrate)
Structure[1]
Crystal structure	Hexagonal (anhydrous) Cubic (dodecahydrate)
Coordination geometry	Octahedral (Al^3+)
Hazards[2]
Safety data sheet	External MSDS
GHS pictograms
GHS signal word	WARNING
GHS hazard statements	H315, H319
GHS precautionary statements	P264, P280, P302+352, P305+351+338, P321, P332+313, P337+313, P362
Flash point	Non-flammable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Ammonium aluminium sulfate, also known as ammonium alum or just alum, is a white crystalline double sulfate usually encountered as the dodecahydrate, formula (NH₄)Al(SO₄)₂·12H₂O. It is used in small amounts in a variety of niche applications. The dodecahydrate occurs naturally as the rare mineral tschermigite.^[1]

Production and basic properties

Ammonium alum is made from aluminium hydroxide, sulfuric acid and ammonium sulfate. It forms a solid solution with potassium alum. Pyrolysis leaves alumina. Such alumina is used in the production of grinding powders and as precursors to synthetic gems.^[3]

Uses

Ammonium alum is not a major industrial chemical or a particularly useful laboratory reagent, but it is inexpensive and nontoxic, which invites many niche applications. It is used in water purification, in vegetable glues, in porcelain cements, in deodorants and in tanning, dyeing and in fireproofing textiles.^[4] The pH of the solution resulting from the topical application of ammonium alum with perspiration is typically in the slightly acid range, from 4 to 5.^[5]

Ammonium alum is a common ingredient in animal repellant sprays.^[6][7][8]

Toxicology

Aluminium sulfate, closely related to ammonium alum, is nontoxic with an LD₅₀ of 6207 mg/kg. No human or ecological (for reduced concentrations) toxicity registered.^[9]

References

1. Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. pp. B–74, B–75. ISBN 0-8493-0462-8..
2. HSNO Chemical Classification Information Database, New Zealand Environmental Risk Management Authority, retrieved 2009-11-23.
3. Otto Helmboldt, L. Keith Hudson, Chanakya Misra, Karl Wefers, Wolfgang Heck, Hans Stark, Max Danner, Norbert Rösch "Aluminum Compounds, Inorganic" in Ullmann's Encyclopedia of Industrial Chemistry 2007, Wiley-VCH, Weinheim.doi:10.1002/14356007.a01_527.pub2
4. "Alum", The Columbia Encyclopedia (6th ed.), Ithaca, NY: Columbia University Press, 2004, retrieved 2009-11-23.
5. Aluminum Ammonium Sulfate Material Safety Data Sheet, J. T. Baker, March 2009, retrieved 2009-11-23.
6. D-TER Animal and Bird Repellent, Bruce Harris Project Management Pty Ltd, 2004-09-04, retrieved 2010-03-03.
7. Multicrop Scat Bird and Animal Repellent Data Sheet (PDF), Multicrop (Aust.) Pty. Ltd., 2003-03-04, retrieved 2010-03-03.
8. Pest Control: Foxes, Tandridge District Council (UK), February 2006, retrieved 2010-03-03.
9. "Ammonium alum", PAN Pesticide Database, Pesticides Action Network, retrieved 2009-11-23.