Extraction and Uses of Metals
5 marks · EasyAluminium and different types of steel are commonly used in construction and for making vehicles.
Explain why aluminium resists corrosion and state one use of aluminium that makes use of this property.
Mild steel and stainless steel are types of steel used in construction. For each type:
i) State ONE typical use.
ii) Explain, for each use, why that type of steel is suitable.
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(a) Aluminium resists corrosion because it forms a strong, thin layer of aluminium oxide that prevents further reaction. One use is outdoor window frames, where corrosion resistance is important. · must show Explanation: oxide layer, Corrosion resistance, One use: e.g. window frames, cables, aeroplane bodies
(b) Mild steel: Used for car bodies or girders because it is strong and easily shaped (malleable). Stainless steel: Used for kitchen sinks because it does not rust (corrosion resistant) and is easy to clean. · must show One use for mild steel, with property relevant to use, One use for stainless steel, with property relevant to use
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Marking points
B1 (a) · 1 mark · Explains that aluminium resists corrosion due to a protective oxide layer.
B2 (a) · 1 mark · States a relevant use based on corrosion resistance (e.g. window frames, overhead cables, aeroplane bodies, outdoor items).
B3 (b) · 1 mark · States one typical use for mild steel and why it is suitable (e.g. car bodies; strong, malleable).
B4 (b) · 1 mark · States one typical use for stainless steel and why it is suitable (e.g. kitchen sinks; does not rust, corrosion resistant).
B5 (b) · 1 mark · Links each use to a relevant property (e.g. malleable for mild steel, corrosion resistance for stainless steel). Accept alternative correct links.
Worked solution
a) Aluminium resists corrosion because it has a thin yet strong oxide layer (aluminium oxide) on its surface. This oxide layer prevents oxygen and water from reaching the metal and stops further corrosion. One use based on this property is overhead electricity cables, which need to be corrosion-resistant since they are exposed to weather.
b) Mild steel is commonly used for car bodies. This is because mild steel is strong yet malleable, allowing it to be shaped into car panels easily and withstand everyday use.
Stainless steel is used for kitchen sinks. This is because it does not rust and is very resistant to corrosion, making it suitable for use with water and easy to clean.