Sodium alum

Sodium alum
Names
IUPAC name
Aluminium sodium bis(sulfate) — water (1:12)
Other names
  • Sodium alum
  • Soda alum
  • E521
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.239 Edit this at Wikidata
EC Number
  • 233-277-3
E number E521 (acidity regulators, ...)
UNII
  • InChI=1S/Al.Na.2H2O4S.12H2O/c;;2*1-5(2,3)4;;;;;;;;;;;;/h;;2*(H2,1,2,3,4);12*1H2/q+3;+1;;;;;;;;;;;;;;/p-4
    Key: ZEMWIYASLJTEHQ-UHFFFAOYSA-J
  • InChI=1/Al.Na.2H2O4S.12H2O/c;;2*1-5(2,3)4;;;;;;;;;;;;/h;;2*(H2,1,2,3,4);12*1H2/q+3;+1;;;;;;;;;;;;;;/p-4
    Key: ZEMWIYASLJTEHQ-XBHQNQODAL
  • [O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[Na+].[Al+3]
Properties[1]
NaAl(SO4)2·12H2O
Molar mass 458.28 g/mol
Appearance white crystalline powder
Density 1.6754 (20 °C)
Melting point 61 °C (142 °F; 334 K)
208 g/100 ml (15 °C)
1.4388
Structure[2]
Cubic, cP96
Pa3, No. 205
a = 1221.4 pm
Octahedral (Na+)
Octahedral (Al3+)
Hazards
Flash point non-flammable
Related compounds
Other cations
 Ammonium aluminium sulfate
Potassium aluminium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Sodium aluminium sulfate is the inorganic compound with the chemical formula NaAl(SO4)2·12H2O (sometimes written Na2SO4·Al2(SO4)3·24H2O). Also known as soda alum, sodium alum, or SAS, this white solid is used in the manufacture of baking powder and as a food additive. Its official mineral name is alum-Na (IMA symbol: Aum-Na[3]).

  1. ^ Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. B-146. ISBN 0-8493-0462-8..
  2. ^ Cromer, D. T.; Kay, M. I.; Larson, A. C. (1 February 1967). "Refinement of the alum structures. II. X-ray and neutron diffraction of NaAl(SO4)2·12H2O, γ-alum". Acta Crystallographica. 22 (2): 182–187. doi:10.1107/S0365110X67000313.
  3. ^ Warr, L.N. (2021). "IMA-CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.