Burnt alum

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Burnt alum is a widely used ingredient in cosmetics, personal care, and skincare formulations. Depending on its function, it may serve as a moisturizer, preservative, emulsifier, or active ingredient to enhance the overall effectiveness and performance of a product.

Burnt alum (Wikipedia)

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. The compound is the most important member of the generic class of compounds called alums, and is often called simply alum.

Potassium alum
Names
IUPAC name
Potassium alum
Other names
  • Potassium alum sulfate
  • Potash alum
  • Alum-(K)
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 °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 is commonly used in water purification, leather tanning, dyeing, 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.

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