Uses of aluminium
2 marks · HardExplain why aluminium does not readily corrode, even though it is a reactive metal.
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Also accept: Aluminium forms a protective oxide layer which prevents further reaction.; A thin, strong aluminium oxide layer forms on the surface.; The oxide layer stops water and air reacting with the metal.
Common mistakes: Aluminium does not react because it is unreactive.; It rusts like iron.; It does not form any oxide layer.
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Marking points
B1 · 1 mark · States or describes that a protective aluminium oxide layer forms on the surface.
B2 · 1 mark · States that the oxide layer prevents water, oxygen or other substances from reaching the aluminium metal (thus stopping futher reaction/corrosion).
Worked solution
Aluminium resists corrosion because it forms a very thin but strong layer of aluminium oxide on its surface.
This oxide layer stops water, air, or other chemicals from reaching the underlying aluminium, preventing further corrosion.