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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)
