Question Constellation Sign up for free AQA · GCSE · Chemistry · Higher
Aluminium alloy corrosion resistance
Explain why aluminium alloy bicycle frames do not need protection from corrosion.
Write your answer first. You can study the marking guidance whenever you need it.
Study the marking See what earns credit and compare it with a full-mark answer.
Marking points
- 1 Identifies the protective oxide coating on aluminium alloy.
- 2 Explains that this barrier prevents the metal contacting water and/or air/oxygen.
Full-mark answer
Aluminium alloy forms a protective oxide coating. This coating prevents water and oxygen from contacting the metal, so further corrosion is prevented.
Why this answer loses marks
Aluminium alloy needs no protection because aluminium is completely unreactive.
Aluminium is reactive; the protection comes from its oxide coating blocking water and oxygen.