AQA GCSE Chemistry Chemistry Paper 1 (Higher), 2023: Question 6

9 marks · Standard Demand difficulty · Extended Answer

Evaluate the use of aluminium, copper, and silver for electrical wires, describe how metals conduct electricity, and explain why alloys do not conduct electricity as well as pure metals.

Practise this question

Question

The image shows a three-part chemistry question about electrical wires. It includes illustrations of overhead power cables, home wiring, and a printed circuit board, along with a table comparing the electrical conductivity, density, and cost of aluminium, copper, and silver. The questions ask students to evaluate the use of these metals based on the table, describe metallic conduction, and explain the effect of alloying on conductivity.
Question text

06 This question is about uses of metals in electrical wires.

Electrical wires can be made from:

• aluminium

• copper

• silver.

Figure 6 shows three uses of electrical wires.

Figure 6

Table 5 shows information about the metals.

The higher the value for electrical conductivity, the better the metal is at

conducting electricity.

Table 5

Aluminium Copper Silver

Electrical conductivity in arbitrary units 37.7 59.6 63.0

Density in g/cm3 2.7 9.0 10.5

Cost of metal per kg in £ 191.50 7.00 640.00

06.1 Evaluate the use of aluminium, copper and silver for the types of electrical wires

shown in Figure 6.

Use Table 5.

[4 marks]

06.2 Describe how metals conduct electricity.

[3 marks]

06.3 Electrical wires are usually made of pure metals and not alloys. This is because pure

metals are better electrical conductors.

Suggest why alloys do not conduct electricity as well as pure metals.

Answer in terms of structure and bonding.

[2 marks]

Mark scheme

Show the mark scheme The mark scheme provides a level-based response guide for the evaluation question, noting points about conductivity, density, and cost. For the description of metallic conduction, it awards marks for mentioning delocalised electrons carrying charge through the structure. For the explanation of alloys, it awards marks for identifying that different sized atoms distort layers and restrict electron movement.

AO/

Question Answers Mark

Spec. Ref

Level 3: A judgement, strongly linked and logically supported by a AO3

06.1 3–4

sufficient range of correct reasons, is given. 4.2.2.7

4.2.2.8

Level 1: Relevant points are made. They are not logically linked. 1–2 4.4.1.2

No relevant content 0

Indicative content

relevant points

• silver is the best electrical conductor

• aluminium is the least dense

• aluminium is the least expensive

• copper is a better conductor than aluminium

or

copper is almost as good a conductor as silver

• copper is much less expensive than silver

• overhead power cables need a low density metal

• wiring in homes needs to be affordable

• printed circuit boards only require small amounts of material

judgements

• use aluminium for overhead wires because of aluminium’s

low density and/or lower cost

• use copper for domestic wiring because copper is a very good

conductor and not too expensive

• use silver only for small uses such as circuit boards due to high

cost

• copper is a good compromise between electrical conductivity and

cost – HEMISTRY – –

AO /

Question Answers Extra information Mark

Spec. Ref.

06.2 (metals have) delocalised 1 AO1

electrons 4.2.1.5

4.2.2.8

20 the electrons carry (electrical) ignore current / electricity for 1

charge charge

the electrons move through the ignore throughout for through 1

structure / metal

AO /

Spec. Ref.

06.3 in alloys different sized atoms 1 AO3

distort the layers / structure 4.2.2.7

4.2.2.8

(so) the movement of 1

(delocalised) electrons is

restricted

– HEMISTRY – –

Total Question 6 9

Question 7

How to answer it

Metals and Electrical Conductivity

What this question tests

This question assesses your ability to evaluate data to justify the use of materials, your understanding of metallic bonding, and how the structure of alloys affects their physical properties.

Part (a) - Question 06.1

Evaluating Metals for Specific Uses

4 Marks

🧠 Exam Technique

An "Evaluate" question requires you to use the data provided to make a judgement. Don't just list numbers; explain why those numbers make a metal suitable for a specific job.

  • Compare the metals (e.g., "Silver is the best conductor but most expensive").
  • Link the property to the use (e.g., "Low density is vital for overhead cables").

✅ Correct Answers (Indicative Content)

  • Aluminium: Use for overhead cables because it has the lowest density (2.7 g/cm³) and is the cheapest (£1.50/kg).
  • Copper: Use for home wiring because it is a much better conductor than aluminium but much cheaper than silver.
  • Silver: Use for printed circuit boards because it is the best conductor (63.0) and only small amounts are needed, so the high cost is less of an issue.

❌ Common Errors

Students often lose marks by not making a final judgement. To get 4 marks, you must clearly state which metal should be used for which purpose and support it with a logical reason from the table.

Part (b) - Question 06.2

How Metals Conduct Electricity

3 Marks

💡 Key Knowledge

Metals consist of a lattice of positive ions surrounded by a "sea" of delocalised electrons. These electrons are free to move throughout the entire structure.

✅ The 3-Step Answer

  1. Metals have delocalised electrons. [1 mark]
  2. These electrons carry electrical charge. [1 mark]
  3. The electrons move through the structure (or metal). [1 mark]

❌ Common Errors

  • "Carrying electricity": The mark scheme specifically says to ignore "carries electricity". You must use the word charge.
  • Moving Ions: Never say the ions move. In a solid metal, the ions are fixed in place; only the delocalised electrons move.

Part (c) - Question 06.3

Conductivity in Alloys

2 Marks

💡 Structure and Bonding

Pure metals have atoms of the same size arranged in regular layers. Alloys contain different sized atoms, which disrupts this regular arrangement.

✅ Correct Answer

  • In alloys, different sized atoms distort the layers or structure. [1 mark]
  • This means the movement of delocalised electrons is restricted or hindered. [1 mark]

🧠 Examiner Commentary

Top-level responses clearly linked the physical distortion of the lattice to the difficulty of electron flow. If the path is "bumpy" because the layers aren't neat, electrons can't flow as easily!

📐 Visualising the Answer

If asked to draw this, you would draw a regular grid of circles for the pure metal. For the alloy, you would draw the same grid but replace a few circles with much larger ones, showing the rows of atoms becoming wavy or "distorted" around the big atoms.

Topics

Chemistry · C2: Bonding, Structure and the Properties of Matter

Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Higher), 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.