AQA GCSE Combined Science: Trilogy Chemistry Paper 1 (Foundation), 2023: Question 5
10 marks · Standard Demand difficulty · Short Answer
Analyze metal extraction processes including electrolysis of aluminium, reduction of titanium with sodium, and reduction of copper oxide with carbon.
Practise this questionQuestion
Question text
05 This question is about extraction of metals.
Aluminium is extracted from a molten mixture of aluminium oxide and cryolite
using electrolysis.
Figure 12 shows the electrolysis cell.
Figure 12
05.1 Complete the sentence.
[1 mark]
The extraction of aluminium is expensive because the process uses
large amounts of .
05.2 Oxygen is produced at the positive carbon electrodes.
The oxygen reacts with the carbon electrodes.
Which gas is produced when oxygen reacts with the positive carbon electrodes?
[1 mark]
Titanium is extracted from titanium chloride by reacting titanium chloride with sodium.
The reaction between titanium chloride and sodium is carried out in an
inert atmosphere.
05.3 Suggest why the reaction is carried out in an inert atmosphere.
[1 mark]
05.4 Complete the sentence.
Choose the answer from the box.
[1 mark]
argon chlorine hydrogen
The gas used for the inert atmosphere is .
05.5 Balance the equation for the reaction.
[1 mark]
TiCl + 4 Na → 24Ti + NaCl
Copper is extracted from copper oxide by reacting copper oxide with carbon.
Figure 13 shows the apparatus.
Figure 13
The equation for the reaction is:
2 CuO(s) + C(s) → 2 Cu(s) + CO2(g)
In an experiment 15.9 g of copper oxide and 1.2 g of carbon reacted.
12.7 g of copper was produced in the reaction.
05.6 Calculate the mass of carbon dioxide produced in this experiment.
[1 mark]
Mass of carbon dioxide = g
05.7 Explain why the mass of the contents in the crucible changed during the experiment.
[2 marks]
05.8 What happens to copper oxide in the reaction?
Give one reason for your answer.
Use the equation for the reaction.
[2 marks]
*24* Tick ( ) one box.
The copper oxide is dissolved
The copper oxide is oxidised
The copper oxide is reduced
Reason
Mark scheme
Show the mark scheme
Question 5
AO /
Question Answers Extra information Mark
Spec. Ref.
05.1 energy / electricity 1 AO1
5.4.3.1
5.4.3.3
AO /
Spec. Ref.
05.2 carbon dioxide 1 AO1
5.4.3.1
5.4.3.3
AO /
Spec. Ref.
05.3 sodium reacts with air / oxygen allow titanium (chloride) reacts 1 AO3
or with air / oxygen 5.1.2.5
sodium is highly reactive 5.4.1.2
AO /
Spec. Ref.
05.4 argon 1 AO3
5.1.2.4
AO /
Spec. Ref.
05.5 TiCl4 + 4 Na → Ti + 4 NaCl allow multiples 1 AO2
5.1.1.1
5.4.1.2
AO /
Spec. Ref.
05.6 4.4 (g) 1 AO2
5.3.1.1
5.3.1.3
AO /
Spec. Ref.
05.7 (the) mass decreased 1 AO2
16 5.3.1.1
(because) carbon dioxide allow (because) carbon dioxide 1 5.3.1.3
escapes (into the atmosphere) is a gas
allow (because) a gas is
produced
AO /
Spec. Ref.
05.8 the copper oxide is reduced 1 AO2
5.4.1.3
(reason)
(copper oxide) loses oxygen 1
Total Question 5 10
How to answer it
Methods of Extracting Metals
What this question tests
This question assesses your understanding of how different metals are extracted based on their reactivity. Key topics include electrolysis of aluminium, displacement reactions for titanium and copper, conservation of mass in chemical reactions, and the definitions of oxidation and reduction.
Aluminium Extraction
💡 Key Knowledge
- Aluminium is more reactive than carbon, so it must be extracted using electrolysis.
- The process requires melting the aluminium oxide, which takes massive amounts of thermal energy.
- Electricity is also used to decompose the compound.
✅ Correct Answers
- 05.1: energy or electricity
- 05.2: carbon dioxide
🧠 Exam Technique: The Anode Reaction
In 05.2, you are asked why the positive electrodes (anodes) wear away. Oxygen gas is produced at the positive electrode. Because the electrode is made of carbon and the cell is very hot, the oxygen reacts with the carbon to form carbon dioxide (CO₂) gas. This is why the anodes must be replaced regularly!
Titanium Extraction & Equations
💡 Key Knowledge
Titanium is extracted using a more reactive metal (sodium). This must be done in an inert atmosphere (using a Noble Gas like Argon) because sodium is extremely reactive and would explode or react with oxygen/water vapor in the air.
✅ Correct Answers
- 05.3: Sodium reacts with air/oxygen (or sodium is highly reactive).
- 05.4: Argon
- 05.5: TiCl₄ + 4 Na → Ti + 4 NaCl
❌ Common Errors
- 05.4: Choosing Hydrogen or Chlorine. Hydrogen is explosive and Chlorine is highly reactive. Only Noble Gases (Group 0) like Argon provide an "inert" (unreactive) atmosphere.
- 05.5: Forgetting to check the chlorine atoms. There are 4 Cl on the left, so you MUST have 4 Cl on the right. This means putting a "4" in front of NaCl.
Copper Extraction & Conservation of Mass
📐 Calculation: Conservation of Mass
The Law of Conservation of Mass states: Total mass of reactants = Total mass of products.
- Identify reactant masses: 15.9g (copper oxide) + 1.2g (carbon) = 17.1g total.
- Identify known product mass: 12.7g (copper).
- Subtract to find the missing gas: 17.1g - 12.7g = 4.4g .
🧠 Explaining Mass Change
When a reaction happens in an open container (like a crucible) and the mass decreases, it is almost always because a gas has been produced and escaped into the atmosphere.
✅ Correct Answer (05.7)
- The mass decreased. 1 Mark
- Because carbon dioxide gas escaped into the atmosphere. 1 Mark
Reduction and Oxidation (Redox)
💡 Key Knowledge: OIL RIG vs Oxygen
While Oxidation Is Loss and Reduction Is Gain (of electrons), at GCSE we also define them by oxygen transfer:
- Oxidation: Gaining oxygen.
- Reduction: Losing oxygen.
✅ Correct Answer
Tick: The copper oxide is reduced
Reason: It loses oxygen (to become copper metal).
❌ Common Errors
Students often say "Copper is reduced." While technically true, the mark scheme specifically looks for Copper Oxide being reduced, as that is the reactant in the equation.
Topics
Chemistry · C1: Atomic Structure and the Periodic Table · C3: Quantitative Chemistry · C4: Chemical Changes
Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Chemistry Paper 1 (Foundation), 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.