Choosing aluminium and copper for their uses
Match each required use with the property that helps it perform that job.
Core and Extended · Chemistry 0620, 2026–2028.
Before you begin
- Define density, electrical conductivity and ductility.
- Distinguish corrosion resistance from a claim of absolute unreactivity.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does ductility help manufacture?
What you will learn
- Explain the required aluminium uses through low density, conductivity and corrosion resistance.
- Explain copper wiring through electrical conductivity and ductility.
Aluminium has several distinct advantages
Aluminium's low density makes it useful in aircraft, since a given material volume has relatively low mass. Actual aircraft structures often use aluminium alloys for suitable strength; the syllabus property link is the low-density advantage, not a claim that pure aluminium alone supplies every design requirement. For overhead electrical cables, low density reduces supported mass and good electrical conductivity enables current flow.
Aluminium is used for food containers because it resists corrosion through its protective surface oxide in ordinary suitable conditions. Resistance is not the same as never reacting with any chemical or being suitable for every food and treatment. The detailed oxide-layer explanation is taught in the Extended reactivity lesson. State the appropriate property for the requested use rather than giving low density as the whole explanation for corrosion resistance.
Copper wiring needs conduction and shaping
Copper is useful for electrical wiring because it has good electrical conductivity and is ductile, so it can be drawn into wires. Conductivity explains current carrying; ductility explains the manufactured shape. Thermal conduction is a different property and should not replace the electrical-conduction reason when the question concerns a wire carrying current.
A material choice usually considers several requirements, such as mass, dimensions and environment, so one favourable property does not prove it is best for every application. With supplied equal-volume density data, mass can be compared by m=ρV. An equal-length comparison alone is not equal volume unless cross-sectional areas also match; do not infer a precise cable mass difference from unspecified dimensions.
Pause and explain
Which property combination belongs to aluminium overhead cables?
Worked example
Explain why aluminium overhead cables and copper wiring are useful, giving the specific property links.
Show the worked solution
- Aluminium conducts electricity and has low density, reducing mass for a given cable volume.
- Copper conducts electricity and is ductile, supporting current flow and drawing into wire.
- Neither explanation establishes that all dimensions or other design requirements are identical.
Answer Aluminium: conductivity and low density. Copper: conductivity and ductility.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Match aluminium aircraft, overhead cables and food containers with their required property reasons.
Give me a hint
The three uses do not all ask for the same single property.
Compare my reasoning
- Aircraft: low density reduces material mass for a given volume.
- Overhead cables: low density and good electrical conductivity.
- Food containers: resistance to corrosion under suitable conditions.
Aircraft low density; cables low density plus electrical conductivity; food containers corrosion resistance.
Look for these in your work
- Every use has its matching reason.
- Corrosion resistance is not confused with low density.
Explain why both electrical conductivity and ductility matter for copper wiring.
Give me a hint
Separate operation of the wire from making its shape.
Compare my reasoning
- Electrical conductivity allows current to pass effectively.
- Ductility allows copper to be drawn into thin wires.
- Thermal conductivity or low density alone would not give both of these required explanations.
Electrical conductivity supports current flow; ductility supports drawing into wire.
Look for these in your work
- Each property has a different role.
- The explanation matches the requested use.
Supplied densities are aluminium 2.7 g/cm³ and copper 8.9 g/cm³. Compare masses for equal 20 cm³ samples and explain why equal wire length alone would not establish the same comparison.
Give me a hint
Use a common volume, and check the missing cross-sectional area in a length-only claim.
Compare my reasoning
- Aluminium mass is 2.7×20=54 g.
- Copper mass is 8.9×20=178 g.
- Equal length gives equal volume only if cross-sectional areas also match; the given mass calculation uses equal volumes explicitly.
54 g aluminium versus 178 g copper; equal length alone does not establish equal volume.
Look for these in your work
- The density calculation uses compatible units.
- The dimensional assumption is stated.
Common mistakes
- Giving thermal rather than electrical conduction as the main current-carrying reason.
- Explaining aircraft only by corrosion resistance and omitting low density.
- Treating corrosion resistance as universal chemical inertness.
- Assuming equal cable lengths guarantee equal volumes.
What can you explain now?
Which two required properties explain copper electrical wiring?
Compare with the explanation
Good electrical conductivity and ductility.
One supports current carrying and the other drawing the material into wires.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain all four required material-use examples. For each, name the property and how it serves the job, then check dimensions in a supplied mass comparison.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.