Aluminium sulfate

Aluminium sulfate
Names
	IUPAC name Aluminium sulfate
	Other names Aluminum sulfate; Aluminium sulphate; Cake alum; Filter alum; Papermaker's alum; Alunogenite; aluminium salt (3:2);
Identifiers
CAS Number	10043-01-3 ; 7784-31-8 (octadecahydrate) ;
3D model (JSmol)	Interactive image;
ChemSpider	23233 ;
ECHA InfoCard	100.030.110
EC Number	233-135-0;
E number	E520 (acidity regulators, ...)
PubChem CID	24850;
RTECS number	BD1700000;
UNII	I7T908772F ; TCS9L00G8F (octadecahydrate) ;
CompTox Dashboard (EPA)	DTXSID2040317 ;
	InChI InChI=1S/2Al.3H2O4S/c;;31-5(2,3)4/h;;3(H2,1,2,3,4)/q2+3;;;/p-6 Key: DIZPMCHEQGEION-UHFFFAOYSA-H ; InChI=1/2Al.3H2O4S/c;;31-5(2,3)4/h;;3(H2,1,2,3,4)/q2+3;;;/p-6 Key: DIZPMCHEQGEION-CYFPFDDLAS;
	SMILES [Al+3].[Al+3].[O-]S(=O)(=O)[O-].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O;
Properties
Chemical formula	Al2(SO4)3
Molar mass	342.15 g/mol (anhydrous) ; 666.44 g/mol (octadecahydrate)
Appearance	white crystalline solid ; hygroscopic
Density	2.672 g/cm3 (anhydrous) ; 1.62 g/cm3 (octadecahydrate)
Melting point	770 °C (1,420 °F; 1,040 K) (decomposes, anhydrous) ; 86.5 °C (octadecahydrate)
Solubility in water	31.2 g/100 mL (0 °C) ; 36.4 g/100 mL (20 °C) ; 89.0 g/100 mL (100 °C)
Solubility	slightly soluble in alcohol, dilute mineral acids
Acidity (pKa)	3.3–3.6
Magnetic susceptibility (χ)	−93.0×10−6 cm3/mol
Refractive index (nD)	1.47
Structure
Crystal structure	monoclinic (hydrate)
Thermochemistry
Std enthalpy of; formation (ΔfH⦵298)	-3440 kJ/mol
Hazards
NFPA 704 (fire diamond)	1 0 0
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	2 mg/m3
IDLH (Immediate danger)	N.D.
Related compounds
Other cations	Gallium sulfate; Magnesium sulfate
Related compounds	See Alum
Supplementary data page
	Aluminium sulfate (data page)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Aluminium sulfate is a salt with the formula Al₂(SO₄)₃. It is soluble in water and is mainly used as a coagulating agent (promoting particle collision by neutralizing charge) in the purification of drinking water and wastewater treatment plants, and also in paper manufacturing.

The anhydrous form occurs naturally as a rare mineral millosevichite, found for example in volcanic environments and on burning coal-mining waste dumps. Aluminium sulfate is rarely, if ever, encountered as the anhydrous salt. It forms a number of different hydrates, of which the hexadecahydrate Al₂(SO₄)₃·16H₂O and octadecahydrate Al₂(SO₄)₃·18H₂O are the most common. The heptadecahydrate, whose formula can be written as [Al(H₂O)₆]₂(SO₄)₃·5H₂O, occurs naturally as the mineral alunogen.

Aluminium sulfate is sometimes called alum or papermaker's alum in certain industries. However, the name "alum" is more commonly and properly used for any double sulfate salt with the generic formula XAl(SO
₄)
₂·12H
₂O, where X is a monovalent cation such as potassium or ammonium.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.