AQA GCSE Chemistry Chemistry Paper 2 (Higher), June 2025: Question 3
9 marks · Standard Demand difficulty · Extended Answer
Evaluate the use of aluminium and wood for making doors, explain how an oxide coating prevents corrosion, and identify the correct composition of a paint formulation.
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Question text
03 Doors can be made from aluminium or wood.
03.1 Table 3 gives information about aluminium and wood.
Table 3
Aluminium Wood
Raw material Metal ore from rock Trees
Relative cost of
87 1
1 kilogram of material
Relative strength 1.3 1.0
No protection needed to Painted to prevent
Protection
prevent corrosion rotting
Melted to form new Shredded into wood
Disposal
products chips for fuel
Evaluate the use of aluminium and of wood for making doors.
[6 marks]
Extra space
03.2 Aluminium has an oxide coating that protects the metal from corrosion.
Explain how the oxide coating protects aluminium from corrosion.
*08* [2 marks]
03.3 Doors made from wood need painting to prevent rotting.
Paints are formulations made by mixing a solid pigment and a liquid.
Which statement describes the composition of a paint?
[1 mark]
Tick ( ) one box.
A fixed mass of pigment and a fixed mass of liquid
A fixed mass of pigment and a variable mass of liquid
A variable mass of pigment and a fixed mass of liquid
A variable mass of pigment and a variable mass of liquid
Mark scheme
Show the mark scheme
Question 3
AO /
Question Answers Mark
Spec. Ref.
03.1 Level 3: A judgement, strongly linked and logically supported by a 5–6 AO3
sufficient range of correct reasons, is given. 4.10.1.1
4.10.1.2
4.10.2.2
Level 2: Some logically linked reasons are given. There may also 3–4 4.10.3.1
be a simple judgement.
Level 1: Relevant points are made. They are not logically linked. 1–2
No relevant content 0
Indicative content
• aluminium ore is a finite resource
• wood is a renewable resource
• aluminium ore has to be mined / quarried
o which causes dust / noise pollution
• trees require land for growing
o which reduces land for farming
o which can lead to deforestation
• cost of wood is lower
o so more doors can be obtained for the same cost
• aluminium is stronger
o so less easily damaged
• aluminium doors do not need painting
o so less maintenance required
• both are recyclable
o so resources are conserved
o so less goes into landfill
o so less fossil fuels used
o so less climate change
• judgement
AO /
Question Answers Extra information Mark
Spec. Ref.
03.2 (the oxide coating) acts as a do not accept sacrificial 1 AO1
barrier protection 4.10.3.1
(that) prevents air / oxygen / do not accept references to 1
water reaching the aluminium / rusting
12 metal do not accept sacrificial
protection
AO /
Spec. Ref.
03.3 a fixed mass of pigment and a 1 AO1
fixed mass of liquid 4.8.1.2
Total Question 3 9
How to answer it
Evaluating Door Materials & Formulations
This question assesses your ability to apply Chemistry knowledge from Using Resources (4.10) and Chemical Analysis (4.8):
- Evaluating materials: Life cycle considerations, finite vs. renewable raw materials, cost, physical properties, and environmental impacts of disposal (Level of Response 6-marker).
- Corrosion prevention: Understanding how natural aluminium oxide coatings protect aluminium without needing sacrificial protection.
- Formulations: Recalling the precise definition of a chemical formulation as a mixture designed as a useful product with carefully measured quantities.
Question 03.1
Evaluate the use of aluminium and of wood for making doors. [6 marks]
💡 Key Knowledge (Data Interpretation)
Organise your evaluation under key life-cycle stages:
- Raw Materials: Aluminium comes from bauxite ore (finite, requires destructive quarrying/mining). Trees are renewable (can be replanted, but need land and can lead to deforestation).
- Cost & Strength: Wood is 87× cheaper per kg (more doors per £). Aluminium is 30% stronger (1.3 vs 1.0), meaning it resists damage and lasts longer.
- Maintenance: Wood rots and must be periodically painted; aluminium naturally resists corrosion.
- Disposal: Both are sustainable at end of life—aluminium is melted and recycled infinitely; wood is burned as a biofuel substitute for fossil fuels.
🧠 Exam Technique (Getting Level 3: 5–6 Marks)
To score full marks on an Evaluate question:
- Give balanced arguments: Discuss advantages and disadvantages of both materials.
- Explain consequences: Don't just quote the table. Say why it matters (e.g., "Aluminium is stronger so it is less easily damaged").
- Include a justified conclusion: End with a clear judgement stating which material you recommend and why.
✅ Model Answer Structure
Raw materials and environment: Aluminium comes from metal ore which is a finite resource, and quarrying causes noise and dust pollution. Wood comes from trees which are renewable; however, farming trees requires land and can cause habitat loss if not managed sustainably.
Manufacturing and performance: Wood is significantly cheaper (relative cost 1 vs 87), meaning far more doors can be produced for the same cost. However, aluminium has higher relative strength (1.3 vs 1.0), making it more durable and resistant to impact damage.
Maintenance and disposal: Wood requires regular painting to prevent fungal decay and rotting, whereas aluminium naturally resists corrosion, requiring less ongoing maintenance. At the end of life, both conserve resources: aluminium can be melted and recycled (saving landfill space and bauxite), while wood can be chipped and used as fuel (reducing fossil fuel use).
Conclusion: Overall, wood is the better choice for residential internal doors due to its much lower cost and renewable source, but aluminium is preferable for high-security exterior doors where strength and low maintenance outweigh the higher initial expense.
❌ Common Errors
- Copying numbers without explanation: Writing "Aluminium cost is 87 and wood is 1" earns Level 1 only. Always add the consequence ("...meaning wood is much cheaper to manufacture").
- Forgetting the conclusion: Missing a final judgement automatically caps your answer below Level 3.
- One-sided answers: Focusing solely on why wood is bad or why aluminium is good.
• Level 3 (5–6 marks): A judgement, strongly linked and logically supported by a sufficient range of correct reasons.
• Level 2 (3–4 marks): Some logically linked reasons given; may include a simple judgement.
• Level 1 (1–2 marks): Relevant points made from the table, but not logically linked.
Question 03.2
Explain how the oxide coating protects aluminium from corrosion. [2 marks]
✅ Correct Answer
- (The aluminium oxide layer) acts as a barrier [1 mark]
- which prevents oxygen / air and water from reaching the aluminium metal underneath [1 mark]
💡 Key Knowledge
Aluminium reacts very quickly with oxygen in the air to form a very thin, tough, and unreactive layer of aluminium oxide (Al₂O₃).
Unlike iron rust (which flakes off and exposes fresh metal), aluminium oxide adheres firmly to the metal surface, sealing it completely against further attack.
❌ Examiner Trap & Rejected Answers
- Do NOT mention "sacrificial protection": Sacrificial protection requires a more reactive metal attached to an object (e.g. zinc blocks on steel ships). The oxide layer is a chemical compound acting as a physical barrier.
- Do NOT say "prevents rusting": Rusting is an exam term strictly reserved for the corrosion of iron and steel only! For any other metal, use the word corrosion.
Question 03.3
Which statement describes the composition of a paint? [1 mark]
✅ Correct Answer
☑ A fixed mass of pigment and a fixed mass of liquid
💡 What is a Formulation?
A formulation is a complex mixture designed as a useful product. In any formulation:
- Each chemical component has a specific function (e.g. pigment for colour, liquid/binder to adhere).
- The components are mixed in carefully measured, exact quantities (fixed masses/ratios) to ensure the product has the exact required properties.
❌ Why Other Options Are Wrong
Any option stating a variable mass is incorrect. If the mass of pigment or liquid varied randomly, the paint would change consistency, dry inconsistently, or produce the wrong shade of colour!
Topics
Chemistry · C8: Chemical Analysis · C10: Using Resources
Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 2 (Higher), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.