Aluminium

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Who discovered it

Ancient Greeks and Romans used aluminium salts as dyeing mordants and as astringents for dressing wounds; alum is still used as a styptic. In 1761 Guyton de Morveau suggested calling the base alum alumine. In 1808, Humphry Davy identified the existence of a metal base of alum, which he at first named alumium and later aluminium (see Spelling section, below).

 Friedrich Wöhler is generally credited with isolating aluminium (Latin alumen, alum) in 1827 by mixing anhydrous aluminium chloride with potassium. The metal, however, had indeed been produced for the first time two years earlier — but in an impure form — by the Danish physicist and chemist Hans Christian Ørsted.

Humphry Davy Hans Christian Ørsted

The extraction of aluminium

The extraction is done by electrolysis. Aluminium oxide has a very high melting point (over 2000°C) and it would be expensive to melt it. So instead it is dissolved in molten cryolite - an aluminium compound with a lower melting point than aluminium oxide. The use of cryolite reduces some of the energy costs involved in extracting aluminium.

   The diagram shows an aluminium oxide electrolysis tank. Both the cathode and the anode are made of graphite, a form of carbon. Aluminium forms at the negative electrode and sinks to the bottom of the tank, where it is tapped off. The equation for this reaction is Al3+ + 3e- Al Oxygen forms at the positive electrodes. The equation for this reaction is 2O2- - 4e- O2 The oxygen reacts with the carbon of the positive electrodes, forming carbon dioxide, and they gradually burn away. Consequently the positive electrodes have to be replaced frequently, which adds to the cost of the process.

Diagram of electrolysis

Info About Aluminium

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Aluminium:

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Is strong, malleable and has a low density.

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Is resistant to corrosion.

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A good conductor of heat and electricity.

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Can be polished to give a highly reflective surface.

A aluminium bar

Uses of Aluminium

 Low density and strength make it ideal for construction of aircraft, lightweight vehicles, and ladders.

 An alloy of aluminium called duralumin is often used instead of pure aluminium because of its improved properties.

 Easy shaping and corrosion resistance make it a good material for drink cans and roofing materials.

 Corrosion resistance and low density leads to its use for greenhouses and window frames.

 Good conduction of heat leads to its use for boilers, cookers and cookware.

 Good conduction of electricity leads to its use for overhead power cables hung from pylons (low density gives it an advantage over copper).

 High reflectivity makes it ideal for mirrors, reflectors and heat resistant clothing for fire fighting.

Aluminium Stuff

Uses for Aluminium Compounds

            Aluminium ammonium sulphate ([Al(NH4)](SO4)2), ammonium alum is used as a mordant, in water purification and sewage treatment, in paper production, as a food additive, and in leather tanning. Aluminium acetate is a salt used in solution as an astringent. Aluminium borate (Al2O3 B2O3) is used in the production of glass and ceramic. Aluminium borohydride (Al(BH4)3) is used as an additive to jet fuel. Aluminium chloride (AlCl3) is used: in paint manufacturing, in antiperspirants, in petroleum refining and in the production of synthetic rubber. Aluminium chlorohydride is used as an antiperspirant and in the treatment of hyperhidrosis. Aluminium fluorosilicate (Al2(SiF6)3) is used in the production of synthetic gemstones, glass and ceramic. Aluminium hydroxide (Al(OH)3) is used: as an antacid, as a mordant, in water purification, in the manufacture of glass and ceramic and in the waterproofing of fabrics. Aluminium oxide (Al2O3), alumina, is found naturally as corundum (rubies and sapphires), emery, and is used in glass making. Synthetic ruby and sapphire are used in lasers for the production of coherent light. Aluminium phosphate (AlPO4) is used in the manufacture: of glass and ceramic, pulp and paper products, cosmetics, paints and varnishes and in making dental cement. Aluminium sulphate (Al2(SO4)3) is used: in the manufacture of paper, as a mordant, in a fire extinguisher, in water purification and sewage treatment, as a food additive, in fireproofing, and in leather tanning. In many vaccines, certain aluminium salts serve as an immune adjuvant (immune response booster) to allow the protein in the vaccine to achieve sufficient potency as an immune stimulant.

Importance of Recycling

   Due to the large energy use in the extraction process, it is vital that we recycle.

Recycled aluminium only requires 5% of the energy needed to extract fresh aluminium.

Remember to recycle, because energy can be better spent.

A customised can Lots of aluminium

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Sources of info

www.picsearch.com

http://en.wikipedia.org/wiki/Humphry_Davy http://en.wikipedia.org/wiki/Hans_Christian_%C3%9 8rsted http://en.wikipedia.org/wiki/Aluminium http://www.gcsechemistry.com/ex16.htm

http://www.bbc.co.uk/schools/gcsebitesize/chemistry /usefulproductsrocks/electrolysisrev3.shtml

Aluminium Wizard