Sodium aluminate 1

Sodium aluminate

Sodium aluminate

Identifiers

CAS number 1302-42-7 [1] 

PubChem 14766 [2]

Jmol-3D images Image 1 [3]

Properties

Molecular formula NaAlO2

Molar mass 81.97 g/mol

Appearance white powder (sometimes light-yellowish)

Density 1.5 g/cm3

Melting point 1650 °C

Solubility in water soluble

Solubility in Alcohol soluble

Refractive index (nD) 1.58

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)

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Infobox references

Sodium aluminate is an important commercial inorganic chemical. It works as an effective source of aluminiumhydroxide for many industrial and technical applications. Pure sodium aluminate (anhydrous) is a white crystallinesolid having a formula variously given as NaAlO2, NaAl(OH)4 (hydrated), Na2O·Al2O3, or Na2Al2O4. Commercialsodium aluminate is available as a solution or a solid.Other related compounds, sometimes called sodium aluminate, prepared by reaction of Na2O and Al2O3 areNa5AlO4 which contains discrete AlO4

5− anions, Na7Al3O8 and Na17Al5O16 which contain complex polymericanions, and NaAl11O17, once mistakenly believed to be β-alumina, a phase of aluminium oxide.[5][6]

StructureAnhydrous sodium aluminate, NaAlO2, contains a three-dimensional framework of corner linked AlO4 tetrahedra.The hydrated form NaAlO2·5/4H2O has layers of AlO4 tetrahedra joined into rings and the layers are held togetherby sodium ions and water molecules that hydrogen bond to O atoms in the AlO4 tetrahedra.[7]

ManufacturingSodium aluminate is manufactured by the dissolution of- aluminium hydroxide in a caustic soda (NaOH) solution. Aluminium hydroxide (gibbsite) can be dissolved in 20–25% aqueous NaOH solution at a temperature near the boiling point. The use of more concentrated NaOH solutions leads to a semi-solid product. The process must be carried out in steam-heated vessels of nickel or steel, and the aluminium hydroxide should be boiled with approximately 50% aqueous caustic soda until a pulp forms. The final mixture has to be poured into a tank and

Sodium aluminate 2

cooled; a solid mass containing about 70% NaAlO2 then forms. After being crushed, this product is dehydrated in arotary oven heated either directly or indirectly by burning hydrogen. The resulting product contains 90% NaAlO2and 1% water, together with 1% free NaOH.

Reaction of aluminium metal and alkaliSodium aluminate is also formed by the action of sodium hydroxide on elemental aluminium which is an amphotericmetal. The reaction is highly exothermic once established and is accompanied by the rapid evolution of hydrogengas. The reaction is sometimes written as:

2 Al + 2 NaOH + 2 H2O → 2 NaAlO2 + 3 H2however the species produced in solution is likely to contain the [Al(OH)4]− ion or perhaps the [Al(H2O)2(OH)4]−.This reaction has been proposed as a potential source of fuel for hydrogen powered cars.

UsesIn water treatment it is used as an adjunct to water softening systems, as a coagulant aid to improve flocculation, andfor removing dissolved silica and phosphates.In construction technology, sodium aluminate is employed to accelerate the solidification of concrete, mainly whenworking during frost.Sodium aluminate is also used in the paper industry, for fire brick production, alumina production and so forth.Sodium aluminate solutions are intermediates in the production of zeolites.[8]

References[1] http:/ / www. commonchemistry. org/ ChemicalDetail. aspx?ref=1302-42-7[2] http:/ / pubchem. ncbi. nlm. nih. gov/ summary/ summary. cgi?cid=14766[3] http:/ / chemapps. stolaf. edu/ jmol/ jmol. php?model=O%3D%5BAl-%5D%3DO. %5BNa%2B%5D[4] http:/ / en. wikipedia. org/ w/ index. php?title=Special:ComparePages& rev1=414397248& page2=Sodium+ aluminate[5] "Identification and characterisation of three novel compounds in the sodium–aluminium–oxygen system", Marten G. Barker, Paul G. Gadd

and Michael J. Begley, J. Chem. Soc., Dalton Trans., 1984, 1139–1146,[6] Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5[7] "The Crystal Structure of Hydrated Sodium Aluminate, NaAlO2·5/4H2O, and Its Dehydration Product", James A. Kaduk, Shiyou Pei, Journal

of Solid State Chemistry, 115, 1, 1995, 126–139,[8] Alan Dyer, (1994), Encyclopedia of Inorganic Chemistry, R. Bruce King (ed.), John Wiley & Sons, ISBN 0-471-93620-0

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Article Sources and ContributorsSodium aluminate  Source: http://en.wikipedia.org/w/index.php?oldid=607201552  Contributors: Anomalocaris, Axiosaurus, Bryan Derksen, David Berardan, Deryck Chan, Epbr123, Foobar,Hermann Luyken, LievenBekaert, Magioladitis, Materialscientist, MiPe, Perfecto, PeterBFZ, Physchim62, Stan J Klimas, Thricecube, Velella, Wavelength, Woodyim9691, Xezbeth, Yakuzai, 17anonymous edits

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