Potassium alum

Potassium alum
Names
IUPAC name
Potassium alum[2]
Other names
  • Potassium alum sulfate
  • Potash alum
  • Alum-(K)[1]
Identifiers
3D model (JSmol)
ChEBI
ECHA InfoCard 100.112.464 Edit this at Wikidata
E number E522 (acidity regulators, ...)
UNII
  • InChI=1S/Al.K.2H2O4S/c;;2*1-5(2,3)4/h;;2*(H2,1,2,3,4)/q+3;+1;;/p-4
  • [O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[Al+3].[K+]
Properties
KAl(SO4)2·12H2O
Molar mass 258.192 g/mol (anhydrous)
474.37 g/mol (dodecahydrate)
Appearance White crystals
Odor Watery metallic
Density 1.725 g/cm3
Melting point 92 to 95 °C (198 to 203 °F; 365 to 368 K)
Boiling point Decomposes at 200[3] °C (392 °F; 473 K)
14.00 g/100 mL (20,5°C)
36.80 g/100 mL (50 °C)
Solubility in other solvents Insoluble in acetone
1.4564
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Potassium alum, potash alum, or potassium aluminium sulfate is a chemical compound first mentioned under various Sanskrit names in Ayurvedic medicinal texts such as charak samhita, sushrut samhita, and ashtang hridaya; is chemically defined as the double sulfate of potassium and aluminium, with chemical formula KAl(SO4)2. It is commonly encountered as the dodecahydrate, KAl(SO4)2·12H2O. It crystallizes in an octahedral structure in neutral solution and cubic structure in an alkali solution with space group Pa3 and lattice parameter of 12.18 Å.[4] The compound is the most important member of the generic class of compounds called alums, and is often called simply alum.[5]

Potassium alum is commonly used in water purification, leather tanning, dyeing,[6] fireproof textiles, and baking powder as E number E522. It also has cosmetic uses as a deodorant, as an aftershave treatment and as a styptic for minor bleeding from shaving.[7][8]

  1. ^ Cite error: The named reference WebMineral was invoked but never defined (see the help page).
  2. ^ International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. Electronic version.
  3. ^ "Material Safety Data Sheet - Aluminum potassium sulfate dodecahydrate". Archived from the original on 25 October 2020. Retrieved 26 July 2020.
  4. ^ "Crystal structure of the alums". Crystallography Open Database. 1934. Archived from the original on 15 April 2018. Retrieved 15 April 2018.
  5. ^ Bottomley, L.; Bottomley, L. A. (2010). Chemistry 1310: Laboratory Manual. Plymouth, Michigan: School of Chemistry & Biochemistry, Georgia Institute of Technology / Hayden-McNeil Publishing. ISBN 978-0-7380-3819-3.
  6. ^ "alum | chemical compound". Britannica.com. Archived from the original on 26 May 2015. Retrieved 18 January 2016.
  7. ^ Helmenstine, Anne Marie. "What is Alum?". About.com. Archived from the original on 14 April 2013. Retrieved 19 April 2013.
  8. ^ "Alum Block for Shaving – When and How to Use One". BlakenBlade.com. Blake'n Blade Shave Shop. Archived from the original on 15 January 2020. Retrieved 15 January 2020.