- Potassium alum
Chembox new
Name = Potassium aluminium sulfate
ImageSize = 200px
OtherNames = potassium alum, potash alum
Section1 = Chembox Identifiers
CASNo = 7784-24-9
Section2 = Chembox Properties
Formula = KAl(SO4)2
MolarMass = 258.207 g/mol
Density = 1.76 g/cm3
Solvent = other solvents
SolubleOther = 36.80 grams of alum/100 grams of water at 50 °C
MeltingPt = 92-93 °C
BoilingPt = 200 °CPotassium alum or potash alum is the
potassium doublesulfate ofaluminium . Its chemical formula is KAl(SO4)2 and it is commonly found in its dodecahydrate form as KAl(SO4)2·12(H2O). It is commonly used inwater purification ,leather tanning, fireprooftextile s, andbaking powder . It also has cosmetic uses as a deodorant and as an aftershave treatment.Characteristics
Potassium alum crystallizes in regular
octahedra with flattened corners, and is very soluble in water. The solution reddenslitmus and is anastringent . When heated to nearly a red heat it gives a porous, friable mass which is known as "burnt alum." It fuses at 92 °C in its ownwater of crystallization . "Neutral alum" is obtained by the addition of as muchsodium carbonate to a solution of alum as will begin to cause the separation of alumina. Alum finds application as amordant , in the preparation of lakes for sizing hand-made paper and in the clarifying of turbid liquids.Mineral form and occurrence
Potassium alum is a naturally occurring sulfate
mineral which typically occurs asencrustation s on rocks in areas ofweathering andoxidation ofsulfide minerals and potassium-bearing minerals.Alunite is an associate and likely potassium and aluminium source. [http://webmineral.com/data/Potassium-alum.shtml Potassium Alum: Mineral Data] [http://www.mindat.org/show.php?id=3267 Mindat] It has been reported atVesuvius ,Italy , east of Springsure,Queensland , Alum Cave,Tennessee , and Alum Gulch,Arizona in theUnited States and the island ofCebu (Philippines) locally known as tawas. A related mineral is "kalinite ", a fibrous mineral with formula KAl(SO4)2·11(H2O). [http://webmineral.com/data/Kalinite.shtml Webmineral]Uses
Potassium alum is an
astringent /styptic andantiseptic . For this reason, it can be used as a naturaldeodorant by inhibiting the growth of thebacteria responsible forbody odor . Use of mineral salts in such a fashion does not preventperspiration . Itsastringent /styptic properties are often employed after shaving and to reduce bleeding in minor cuts and abrasions,nosebleeds , andhemorrhoids . It is frequently used topically and internally in traditional systems of medicine includingAyurveda , where it is called phitkari or saurashtri, andTraditional Chinese Medicine , where it is called ming fan. [http://tcm.health-info.org/Herbology.Materia.Medica/mingfan-properties.htm Uses of Alum in Traditional Chinese Medicine]References
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