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Aluminium
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Who discovered it
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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
 Aluminium:
 Is
strong, malleable and has a low density.
 Is resistant to corrosion.
 A good conductor of heat and electricity.
 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.
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Aluminium Stuff
Uses for Aluminium Compounds
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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
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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
Sources of info
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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