View source for Aluminium sulfate

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{{chembox
| Name = Aluminium sulfate (anhydrous)
| ImageFile = Aluminium sulfate.jpg
|   ImageSize = 200px
|   ImageName = Aluminium sulfate hexadecahydrate
| IUPACName = Aluminium sulfate
|   OtherNames = Cake alum<br />Filter alum<br />Papermaker's alum<br />Alunogenite<br/>Sulfuric acid, aluminum salt (3:2)
| Section1 = {{Chembox Identifiers
|   CASNo = 10043-01-3
|    CASNo_Ref = {{cascite}}
|   PubChem = 24850
|   EINECS = 233-135-0
|   RTECS = BD1700000
|   ChemSpiderID = 23233
|   InChI = 1/2Al.3H2O4S/c;;3*1-5(2,3)4/h;;3*(H2,1,2,3,4)/q2*+3;;;/p-6
|   InChIKey = DIZPMCHEQGEION-CYFPFDDLAS
|   StdInChI = 1S/2Al.3H2O4S/c;;3*1-5(2,3)4/h;;3*(H2,1,2,3,4)/q2*+3;;;/p-6
|   StdInChIKey = DIZPMCHEQGEION-UHFFFAOYSA-H
  }}
| Section2 = {{Chembox Properties
|   Reference = <ref name="RubberBible">{{RubberBible62nd|page=B-74}}.</ref>
|   Formula = Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>
|   MolarMass = 342.15 g/mol
|   Appearance = white crystalline solid, hygroscopic
|   Density = 2.71 g/cm<sup>3</sup>
|   Solubility = 31.3 g/100 ml (0 °C)<br/>36.4 g/100 ml (20 °C)<br/>98.1 g/100 ml (100 °C)
|   SolubleOther = slightly soluble in [[alcohol]], dilute mineral [[acid]]s
|   MeltingPt = 770 °C ''decomp.''
|   RefractIndex = 1.47 
  }}
| Section7 = {{Chembox Hazards
|   Reference = <ref>{{GHS class NZ|id=9476|accessdate=2009-11-25}}.</ref>
|   EUIndex = not listed
|   GHSPictograms = {{GHS corrosion|Corr. Met. 1; Eye Dam. 1}}{{GHS07|Acute Tox. 4 (oral); Skin Irrit. 2}}{{GHS09|Aquatic Chronic 2}}
|   GHSSignalWord = DANGER
|   HPhrases = {{H-phrases|290|302|315|318|411}}
|   PPhrases = {{P-phrases|234|264|270|273|280| 301+312|302+352|305+351+338|310|321|330|332+313|337+313|362|390|391|406|501}}
|   FlashPt = non-flammable
|   ExternalMSDS = {{ICSC-small|1191}}
  }}
| Section8 = {{Chembox Related
|   OtherCations = [[Gallium sulfate]]<br/>[[Indium sulfate]]<br/>[[Thallium sulfate]]
|   OtherCpds = ''See'' [[Alum]]
  }}
}}
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{{chembox
| Name = Aluminium sulfate octadecahydrate
| ImageFile = Aluminium sulfate.jpg
|   ImageSize = 200px
|   ImageName = Aluminium sulfate hexadecahydrate
| IUPACName = Aluminium sulfate — water (1:18)
|   OtherNames = [[Alunogenite]]
| Section1 = {{Chembox Identifiers
|   CASNo = 7784-31-8
|   CASNo_Ref = {{cascite}}
|   EINECS = 233-135-0
|   RTECS = BD1700000
|   ChemSpiderID = 
|   InChI = 
|   InChIKey = 
|   StdInChI = 
|   StdInChIKey = 
  }}
| Section2 = {{Chembox Properties
|   Reference = <ref name="RubberBible"/>
|   Formula = Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·18H<sub>2</sub>O
|   MolarMass = 666.42 g/mol
|   Appearance = white crystalline solid
|   Density = 1.69 g/cm<sup>3</sup>
|   Solubility = 
|   SolubleOther = 
|   MeltingPt = 86.5 °C
|   RefractIndex = 1.47 
  }}
| Section3 = {{Chembox Structure
|   Coordination =
|   CrystalStruct = [[monoclinic]]
  }}
}}
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'''Aluminium sulfate''', [[Aluminium|Al]]<sub>2</sub>([[Sulfur|S]][[Oxygen|O<sub>4</sub>]])<sub>3</sub>, is an industrial chemical used as a [[Flocculation|flocculating agent]] in the purification of drinking water<ref>{{citation | webpage = Conventional Coagulation-Flocculation-Sedimentation | website = Safe Drinking Water is Essential | publisher = National Academy of Sciences | date = 2007 | url = http://drinking-water.org/html/en/Treatment/Coagulation-Flocculation-technologies.html | accessdate = 2007-12-01 }}.</ref><ref>{{citation | last1 = Kvech | first1 = S. | last2 = Edwards | first2 = M. | title = Solubility controls on aluminum in drinking water at relatively low and high pH | journal = Water Res. | volume = 36 | issue = 17 | year = 2002 | pages = 4356–68 | doi = 10.1016/S0043-1354(02)00137-9 }}.</ref> and waste water treatment plants, and also in paper manufacturing.

Aluminium sulfate is sometimes incorrectly referred to as [[alum]] but alums are closely related compounds typified by KAl(SO<sub>4</sub>)<sub>2</sub><sup>.</sup>12H<sub>2</sub>O. The anhydrous form occurs naturally as a rare [[mineral]] [[millosevichite]], found e.g. in volcanic environments and on burning coal-mining waste dumps. Aluminium sulfate is rarely, if ever, encountered as the anhydrous salt. It forms a number of different [[hydrate]]s, of which the hexadecahydrate Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·16H<sub>2</sub>O and octadecahydrate Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·18H<sub>2</sub>O are the most common. The heptadecahydrate, whose formula can be written as [Al(H<sub>2</sub>O)<sub>6</sub>]<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·5H<sub>2</sub>O, occurs naturally as the mineral [[alunogenite]].

==Preparation==

Aluminium sulfate may be made by [[aluminium hydroxide]], Al(OH)<sub>3</sub>, in [[sulfuric acid]], H<sub>2</sub>SO<sub>4</sub>:

:2 Al(OH)<sub>3</sub> + 3 H<sub>2</sub>SO<sub>4</sub> → Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·6H<sub>2</sub>O

==Uses==

Aluminium Sulfate is used in [[water purification]] and as a [[mordant]] in dyeing and printing textiles.  In water purification, it causes impurities to coagulate which are removed as the particulate settles to the bottom of the container or more easily filtered. This process is called [[coagulation]] or [[flocculation]].

When dissolved in a large amount of neutral or slightly-alkaline water, aluminium sulfate produces a gelatinous precipitate of [[aluminium hydroxide]], Al(OH)<sub>3</sub>.  In dyeing and printing cloth, the gelatinous precipitate helps the dye adhere to the clothing fibers by rendering the pigment insoluble.

Aluminium sulfate is sometimes used to reduce the [[pH]] of garden soil, as it [[Hydrolysis|hydrolyzes]] to form the aluminium hydroxide precipitate and a dilute [[sulfuric acid]] solution. An example of what changing the pH level of soil can do to plants is visible when looking at the Hydrangea macrophylla. The gardener can add Aluminum sulfate to the soil to reduce the pH level which in turn will result in the flowers of the Hydrangea turning a different color.

Aluminium sulfate is the active ingredient of some [[antiperspirant]]s; however, beginning in 2005 the US [[Food and Drug Administration]] no longer recognized it as a wetness reducer.

Aluminium sulfate is usually found in [[baking powder]], where there is controversy over its use due to concern regarding the safety of adding aluminum to the diet.

In construction industry it is used as waterproofing agent and accelerator in [[concrete]]. Another use is a foaming agent in [[fire fighting foam]].

It is also used in [[Styptic|styptic pencils]], and pain relief from stings and bites; it is the active ingredient in popular pain relief products such as [[Stingose]].

It can also be very effective as a [[molluscicide]], killing [[spanish slug]]s.

==Chemical Reactions==
The compound decomposes to [[alumina|γ−alumina]] and [[sulfite]] when heated between 580 and 900°C. It combines with water forming hydrated salts of various compositions. 

Produces [[calcium aluminate]] with the evolution of sulfate when calcined with [[calcium sulfate]]:{{Citation needed|date=August 2009}}
: Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + CaSO<sub>4</sub> → Ca(AlO<sub>2</sub>)<sub>2</sub> + 4 SO<sub>3</sub>{{Citation needed|date=August 2009}}

Aluminium sulfate reacts with [[sodium bicarbonate]] to which foam stabilizer has been added, typically made from saponin, licorice root, or hydrolyzed animal protein in aqueous solution, forming fire-extinguishing foams, producing [[carbon dioxide]]
: Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + 6 NaHCO<sub>3</sub> → 2 Al(OH)<sub>3</sub> + 3 Na<sub>2</sub>SO<sub>4</sub> + 6 CO<sub>2</sub>

The carbon dioxide is trapped by the foam stabilizer and creates a thick foam which will float on top of hydrocarbon fuels and seal off access to atmospheric oxygen, smothering the fire. Chemical foam was unsuitable for use on polar solvents such as alcohol, as the fuel would mix with and break down the foam blanket. The carbon dioxide generated also served to propel the foam out of the container, be it a portable fire extinguisher or fixed installation using hoselines. Chemical foam is considered obsolete in the United States and has been replaced by synthetic mechanical foams, such as AFFF which have a longer shelf life, are more effective, and more versatile, although some counties such as Japan and India continue to use it.

==References==
===Footnotes===
{{reflist}}
===Notations===
*{{cite book | author=Pauling, Linus | title=General Chemistry | location=W.H. Freeman | publisher=San Francisco | year=1970 | isbn=0-486-65622-5}}

==External links==
*{{ICSC|1191}}
*{{HSDB|name=Aluminum sulfate}}
*{{PGCH|0024}}
*{{EHC|194|name=Aluminium}}
*{{JEFCA-mono|url=http://www.inchem.org/documents/jecfa/jecmono/v024je07.htm | name=Aluminium | whoseries=24}}
* [http://www.agr.gc.ca/pfra/water/alhealth_e.htm Aluminum and health]

[[Category:Aluminium compounds]]
[[Category:Sulfates]]
[[Category:Molluscicides]]
[[Category:Water treatment]]

{{Imported from Wikipedia|name=Aluminium sulfate|id=327353240}}