Preparation, properties and uses of aluminium

Aluminium (Al) :
Ores of Aluminium

  • Corundum Al2O3
  • Diaspore Al2O3.H2O
  • Bauxite Al2O3.2H2O
  • Gibsite Al2O3.3H2O

Bauxite can be purified by three methods

  • Bayer's process
  • Hall's process
  • Serpeck's process

Bayer's process :
It contains Fe2O3(Iron oxide) as impurity

Hall's process :

Serpeck's process :
Alumina reacts with silicon dioxide in the presence of carbon to produce silicon carbide and carbon monoxide.

Hall–Heroult's process :
Electrolyte :

In this method cyolite increases conducitivity and decreases the melting point.
Cathode : Fe
Anode : Graphite
Na_{3}AlF_{6} \rightarrow 3NaF + AlF_{3}
AlF_{3} \rightarrow Al^{+3} + 3F^{-}
At cathode : Al^{+3} + 3e^{-} \rightarrow Al
At anode : 12F^{-} \rightarrow 6F_{2} + 12e^{-}
Thermite process :
In this process BaO2 + Al mixture is used as ignition mixture and 3 : 1 (Fe2O3 and Al) is used as thermite mixture.

AlCl_{3} + 3H_{2}O \rightarrow Al(OH)_{3} + 3HCl

View the Topic in this Video from 0:07 to 1:16

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