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CH1012
ALUMINA
Aluminium
Oxide (alumina), Al2O3.
• occurs in nature
as the mineral corundum.
• occurs in forms containing traces of other metal ions such as the gem stones:
ruby (Cr3+) & blue sapphire (Fe2+, Fe3+, Ti4+).
ruby (Cr3+) & blue sapphire (Fe2+, Fe3+, Ti4+).
• Bauxite Al2O3.nH2O +
SiO2,
Fe2O3,
TiO2 is the major source of alumina for aluminium.
• Alumina is amphoteric.
Al2O3(s) + 6H+(aq) ® 2Al3+(aq) + 3H2O(l)
Al2O3(s) + 2OH-(aq) + 3H2O(l) ®
2Al(OH)4-(aq)
