View source for Potassium aluminium sulfate

{{Redirect|Potassium alum|the mineral form|Alum-(K)}}
{{FixBunching|beg}}
{{chembox
| verifiedrevid = 263158583
| Name = Potassium aluminium sulfate dodecahydrate
| ImageFile = Síran hlinito-draselný.PNG
|   ImageSize =
|   ImageName = Aluminium potassium sulfate
| IUPACName = Aluminium potassium bis(sulfate) — water (1:12)
|   OtherNames = Potassium alum<br/>Potash alum<br/>Alum<br/>[[Kalinite]]
| Section1 = {{Chembox Identifiers
|   CASNo = 7784-24-9 <!-- Aldrich-validated -->
|   ChemSpiderID = 56418
|   EC-number = 233-141-3
|   InChI = {{InChIwrap|1/Al.K.2H2O4S.12H2O/c;;2* 1-5(2,3)4;;;;;;;;;;;;/h;;2*(H2 ,1,2,3,4);12*1H2/q+3;+1;;;;;;;<br/>;;;;;;;/p-4}}
|   InChIKey = GNHOJBNSNUXZQA-XBHQNQODAI
|   StdInChI = {{InChIwrap|1S/Al.K.2H2O4S.12H2O/c;;2 *1-5(2,3)4;;;;;;;;;;;;/h;;2*(H 2,1,2,3,4);12*1H2/q+3;+1;;;;;;<br/>;;;;;;;;/p-4}}
|   StdInChIKey = GNHOJBNSNUXZQA-UHFFFAOYSA-J
  }}
| Section2 = {{Chembox Properties
|   Reference = <ref>{{RubberBible62nd|page=B-130}}.</ref>
|   Formula = KAl(SO<sub>4</sub>)<sub>2</sub>·12H<sub>2</sub>O
|   MolarMass = 474.39 g/mol
|   Density = 1.757 g/cm<sup>3</sup> (20 °C)
|   Solubility = 11.4 g/100 ml (20 °C)
|   MeltingPt = 64.5 °C (−9H<sub>2</sub>O)<br/>92.5 °C 
|   BoilingPt = 200 °C ''dehydr.''
|   RefractIndex = 1.454
  }}
| Section3 = {{Chembox Structure
|   Reference = <ref>{{citation | first1 = S. C. | last1 = Nyburg | first2 = J. W. | last2 = Steed | first3 = S. | last3 = Aleksovska | first4 = V. M. | last4 = Petrusevski | title = Structure of the alums. I. On the sulfate group disorder in the &alpha;-alums | journal = Acta Crystallogr. Sect. B: Struct. Sci. | year = 2000 | volume = B56 | issue = 2 | pages = 204–9 | doi = 10.1107/S0108768199014846}}.</ref>
|   CrystalStruct = Cubic, [[Pearson symbol|cP96]]
|   SpaceGroup = Pa<u style="text-decoration:overline">3</u>, No. 205
|   Coordination = Octahedral (K<sup>+</sup>)<br/>Octahedral (Al<sup>3+</sup>)
|   LattConst_a = 1216.40(5) pm
  }}
| Section7 = {{Chembox Hazards
|   EUIndex = not listed
|   FlashPt = non-flammable
  }}
| Section8 = {{Chembox Related
|   OtherCations = [[Sodium aluminium sulfate]]<br/>[[Ammonium aluminium sulfate]]<br/>[[Potassium chromium(III) sulfate]]
  }}
}}
{{FixBunching|mid}}
{{chembox
| verifiedrevid = 263158583
| Name = Potassium aluminium sulfate (anhydrous)
| ImageFile = Síran hlinito-draselný.PNG
|   ImageSize =
|   ImageName = Aluminium potassium sulfate
| IUPACName = Aluminium potassium bis(sulfate)
| Section1 = {{Chembox Identifiers
|   CASNo = 10043-67-1
|    CASNo_Ref = {{cascite}}
|   ChemSpiderID = 23239
|   EC-number = 233-141-3
|   InChI = 1/Al.K.2H2O4S/c;;2*1-5(2,3)4/h;;2*(H2,1,2,3,4)/q+3;+1;;/p-4
|   InChIKey = GRLPQNLYRHEGIJ-XBHQNQODAE
|   StdInChI = 1S/Al.K.2H2O4S/c;;2*1-5(2,3)4/h;;2*(H2,1,2,3,4)/q+3;+1;;/p-4
|   StdInChIKey = GRLPQNLYRHEGIJ-UHFFFAOYSA-J
  }}
| Section2 = {{Chembox Properties
| Formula = KAl(SO<sub>4</sub>)<sub>2</sub>
|   MolarMass = 258.21 g/mol
|   Density = 
|   Solubility = 
|   MeltingPt = 
|   BoilingPt = 
  }}
| Section7 = {{Chembox Hazards
|   Reference = <ref>{{GHS class NZ|id=6182|accessdate=2009-11-28}}.</ref>
|   EUIndex = not listed
|   GHSPictograms = {{GHS exclamation mark|Acute Tox. 4 (oral); Skin Irrit. 2; Eye Irrit. 2}}{{GHS corrosion|Corr. Met. 1}}
|   GHSSignalWord = WARNING
|   HPhrases = {{H-phrases|302|315|319}}
|   PPhrases = {{P-phrases|234|264|270|280 |301+312|302+352|305+351+338|321|330|332+313|337+313|362|390|406|501}}
|   FlashPt = non-flammable
  }}
}}
{{FixBunching|end}}
'''Potassium aluminium sulfate''', better known as '''potassium alum''' or '''potash alum''', is the [[double sulfate]] of [[aluminium]] and [[potassium]]. Its chemical formula is KAl(SO<sub>4</sub>)<sub>2</sub> and it is commonly found in its [[hydrate|dodecahydrate]] form as KAl(SO<sub>4</sub>)<sub>2</sub>·12(H<sub>2</sub>O). The dodechydrate is sometimes commercialised as '''alum''': this name is ambiguous in [[chemical nomenclature]], as potassium aluminium sulfate is one of several [[alum]]s (double sulfates of aluminium with a monovalent cation). It is commonly used in [[water purification]], [[leather]] tanning, fireproof [[textile]]s, and [[baking powder]]. It also has uses as a deodorant, as an aftershave treatment and as [[acidity regulator]] in food (E522).

==Characteristics==
Potassium alum crystallizes in regular [[octahedra]] with flattened corners, and is very soluble in water. The solution reddens [[litmus]] and is an [[astringent]]. 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 own [[water of crystallization]]. "Neutral alum" is obtained by the addition of as much [[sodium carbonate]] to a solution of alum as will begin to cause the separation of alumina. Alum finds application as a [[mordant]], in the preparation of lakes for sizing hand-made paper and in the clarifying of turbid liquids.

==Mineral form and occurrence==
The mineral form of potassium alum is officially known as [[alum-(K)]].<ref>{{citation | title = Tidying up mineral names: an IMA-CNMNC scheme for suffixes, hyphens and diacritical marks | url = http://pubsites.uws.edu.au/ima-cnmnc/tidyingupnames.pdf | first = Ernst A.J. | last = Burke | journal = Mineralogical Record | volume = 39 | issue = 2 | year = 2008 | pages = 131–35}}.</ref> It is a naturally occurring [[sulfate mineral]] which typically occurs as [[encrustation]]s on rocks in areas of [[weathering]] and [[oxidation]] of [[sulfide]] minerals and potassium-bearing minerals. <ref>{{MinDat-ref | name = Alum-(K) | id = 3267 | accessdate = 2009-11-28}}. {{WebMineral-ref | name = Alum-(K) | url = http://webmineral.com/data/Alum-%28K%29.shtml | accessdate = 2009-11-28}}.</ref> It has been reported at 
*[[Vesuvius]], [[Italy]]
*east of Springsure, [[Queensland]]
*Alum Cave, [[Tennessee]]
*Alum Gulch, [[Arizona]]
*the island of [[Cebu]] (Philippines), locally known as ''tawas''. 

[[Kalinite]], a fibrous mineral, was once thought to be the undecahydrate, but is now believed to be chemically identical to Alum-(K).<ref>{{MinDat-ref | name = Kalinite | id = 2137 | accessdate = 2009-11-28}}. {{WebMineral-ref | name = Kalinite | url = http://webmineral.com/data/Kalinite.shtml | accessdate = 2009-11-28}}.</ref>

==Uses==
Potassium alum is an [[astringent]]/[[styptic]] and [[antiseptic]].  For this reason, it can be used as a natural [[deodorant]] by inhibiting the growth of the [[bacteria]] responsible for [[body odor]].  Use of mineral salts in such a fashion does not prevent [[perspiration]].  Its [[astringent]]/[[styptic]] properties are often employed after shaving and to reduce bleeding in minor cuts and abrasions, [[Epistaxis|nosebleeds]], and [[hemorrhoids]].  It is frequently used topically and internally in traditional systems of medicine including [[Ayurveda]], where it is called ''phitkari'' or ''saurashtri'', and [[traditional Chinese medicine]], where it is called ''ming fan''.<ref>{{citation | url = http://tcm.health-info.org/Herbology.Materia.Medica/mingfan-properties.htm | title = Uses of Alum in Traditional Chinese Medicine | accessdate = 2009-11-28}}.</ref>

==References==
{{reflist}}

==External links==
*{{PGCH|0024}}
*{{EHC|194|name=Aluminium}}
*{{HSDB|name=Alum, potassium}}
*{{JEFCA-mono|url=http://www.inchem.org/documents/jecfa/jecmono/v024je07.htm | name=Aluminium | whoseries=24}}

[[Category:Aluminium compounds]]
[[Category:Potassium compounds]]
[[Category:Sulfates]]
[[Category:Water treatment]]
[[Category:Acidity regulators]]
[[Category:Stabilizers]]

{{Imported from Wikipedia|name=Potassium alum|id=326855538}}