AQA GCSE Chemistry Chemistry Paper 1 (Foundation), June 2025: Question 3

8 marks · Low Demand difficulty · Short Answer

Analyze electrochemical cells, determine metal reactivity from cell voltages, calculate the number of cells in a battery, and identify key properties of fuel and rechargeable cells.

Practise this question

Question

Figure 3 illustrates a simple chemical cell with a copper electrode and a metal electrode immersed in an electrolyte and connected to a voltmeter. Table 2 shows the voltage in volts produced with different metal electrodes: A gives 1.1 V, B gives 0.0 V, C gives 0.8 V, and D gives 2.7 V. Six sub-questions ask about: selecting a suitable electrolyte, identifying which metal is copper with a reason, listing the metals in order of reactivity, calculating the number of 3.6 V cells required to produce 14.4 V, completing a sentence on the product of a hydrogen fuel cell, and describing what happens to the chemical reaction when a cell is recharged.
Question text

03 Cells contain chemicals that react to produce electricity.

A student investigated the voltage produced by four different cells.

Figure 3 shows the apparatus.

Figure 3

This is the method used.

1. Measure the voltage produced by the cell using metal A as the metal electrode.

2. Repeat using different metals as the metal electrode.

Table 2 shows the results.

Table 2

Metal electrode Voltage in volts

A 1.1

B 0.0

C 0.8

D 11 2.7

03.1 Which substance could be used as the electrolyte in the cell in Figure 3?

[1 mark]

Tick ( ) one box.

*10Pure water*

Sodium chloride solution

Solid potassium bromide

03.2 Which metal A, B, C or D was copper?

Give one reason for your answer.

Use Figure 3 and Table 2.

[2 marks]

Metal

Reason

03.3 Write the four metals A, B, C and D in order of reactivity.

Use Table 2.

[1 mark]

Most reactive

Least reactive 12

03.4 A battery consists of several cells connected together in series.

Each cell has a voltage of 3.6 V.

Calculate the number of cells needed to make a battery of voltage 14.4 V.

[2 marks]

Number of cells =

03.5 Fuel cells can be used to power electric cars.

Complete the sentence.

Choose the answer from the box.

[1 mark]

ammonia methane water

The overall reaction in a hydrogen fuel cell involves the oxidation of

hydrogen to produce .

03.6 Rechargeable cells can be recharged when an external electrical current is supplied.

Complete the sentence.

[1 mark]

When an external electrical current is supplied to a rechargeable cell,

the chemical reaction is .

Mark scheme

Show the mark scheme Mark scheme for Question 3 showing answers for parts 03.1 to 03.6. Part 03.1 gives 'sodium chloride solution' (1 mark). Part 03.2 gives metal 'B' (1 mark) and the reason 'the two metals must be different' or allowing 'the voltage is 0.0 V' (1 mark). Part 03.3 gives the order D, A, C, B from most to least reactive (1 mark). Part 03.4 gives working 14.4 / 3.6 (1 mark) and answer 4 (1 mark). Part 03.5 gives 'water' (1 mark). Part 03.6 gives 'reversed' (1 mark). Total marks: 8.

Question 3

AO /

Question Answers Extra information Mark

Spec. Ref.

03.1 sodium chloride solution 1 AO2

4.4.3.1

4.5.2.1

AO /

Spec. Ref.

03.2 (metal)

B 1 AO3

4.5.2.1

(reason)

the two metals must be different allow the voltage is 0.0 V 1

(to produce a voltage)

MP2 is dependent upon the

award of MP1

AO /

Spec. Ref.

03.3 (most reactive) D 1 AO3

A 4.5.2.1

C

(least reactive) B

AO /

Spec. Ref.

03.4 14.4 1 AO2

(number of cells = ) 4.5.2.1

3.6

= 4 1

AO /

Spec. Ref.

03.5 water 1 AO1

4.5.2.2

AO /

Spec. Ref.

03.6 reversed ignore faster 1 AO1

4.5.2.1

Total Question 3 8

How to answer it

Electrochemical Cells and Fuel Cells

📌 What this question tests

This question assesses your understanding of Topic 5: Energy Changes (Chemical Cells and Fuel Cells). Specifically:

  • Identifying suitable electrolytes (substances containing free-moving ions).
  • Understanding how the difference in reactivity between two electrodes determines cell voltage.
  • Deducing a reactivity series from cell potential data.
  • Simple series battery voltage calculations.
  • Core recall of the reaction products in a hydrogen fuel cell and what happens during the recharging of rechargeable cells.

Part (a) — Question 03.1

Identifying a Suitable Electrolyte [1 Mark]

✅ Correct Answer

Sodium chloride solution (ticked)

1 Mark: Exactly one tick in the box for "Sodium chloride solution".

💡 Key Knowledge

  • An electrolyte is an ionic compound that conducts electricity because its ions are free to move.
  • In solutions or molten liquids, ions can move and carry charge.
  • Pure water contains almost entirely neutral molecules (very few ions) and conducts poorly.

❌ Common Errors

  • Solid potassium bromide: Even though it is ionic, the ions are held in a fixed giant lattice and cannot move.
  • Pure water: Distilled/pure water is a covalent molecular liquid without sufficient ions to conduct an electric current.

🧠 Exam Technique

Always look for two words: ionic and solution (or liquid/molten). If it says "solid", it cannot be an electrolyte!

Part (b) — Question 03.2

Identifying Copper from Voltage Data [2 Marks]

✅ Correct Answer

Metal: B

Reason: The two metals must be different to produce a voltage (or "the voltage is 0.0 V").

Mark 1: Identifying metal B.
Mark 2: Correct explanation (Mark 2 depends on scoring Mark 1).

💡 Key Knowledge

  • A simple chemical cell requires two different metals dipped in an electrolyte.
  • Voltage is produced because of the difference in the metals' tendency to lose electrons (reactivity).
  • If both electrodes are made of the same metal (copper and copper), the difference in reactivity is zero, so the voltage produced is 0.0 V.

❌ Common Errors

  • Choosing metal D because it has the highest voltage (confusing "highest reading" with "same metal").
  • Giving a vague reason like "it doesn't react" or "it has no electricity" without stating that identical metals produce zero potential difference.

Part (c) — Question 03.3

Ordering Metals by Reactivity [1 Mark]

✅ Correct Answer

Most reactive:

  1. D (2.7 V)
  2. A (1.1 V)
  3. C (0.8 V)
  4. B (0.0 V — copper)

Least reactive

1 Mark: All four letters in the exact sequence: D, A, C, B.

💡 Key Knowledge

  • One electrode is fixed as copper throughout the experiment.
  • The greater the difference in reactivity between copper and the other metal, the higher the voltage produced.
  • Since copper is very low in reactivity, metals that give large positive voltages must be further above copper in the reactivity series.

🧠 Exam Technique

  • Check the order required: most reactive at the top to least reactive at the bottom.
  • Rank by voltage in descending order: 2.7 V > 1.1 V > 0.8 V > 0.0 V.

Part (d) — Question 03.4

Calculating Cells in a Battery [2 Marks]

📐 Step-by-Step Calculation

  1. Identify formula:
    Total Voltage = Number of Cells × Voltage per Cell
  2. Rearrange:
    Number of cells = 14.4 / 3.6
  3. Calculate answer:

    Number of cells = 4

Mark 1: Working showing 14.4 / 3.6 .
Mark 2: Final answer of 4.

🧠 Exam Technique

  • A battery is two or more cells connected in series. Their voltages add up.
  • Always write down the division step on the working lines. If you write only an incorrect final number, you lose both marks. Showing 14.4 / 3.6 secures 1 method mark even if an arithmetic slip occurs.

Part (e) — Question 03.5

Hydrogen Fuel Cell Reaction Product [1 Mark]

✅ Correct Answer

water

"The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water."

1 Mark: Word chosen correctly from the box.

💡 Key Knowledge

  • Overall reaction:
    2H₂ + O₂ → 2H₂O
  • Hydrogen is oxidised (gains oxygen / loses electrons).
  • A major environmental advantage of hydrogen fuel cells over fossil fuels is that only water is produced, with no greenhouse gas emissions (like CO₂) at point of use.

Part (f) — Question 03.6

Recharging a Cell [1 Mark]

✅ Correct Answer

reversed

"When an external electrical current is supplied to a rechargeable cell, the chemical reaction is reversed."

1 Mark: Word stating the reaction goes backwards / is reversed.

💡 Key Knowledge

  • Non-rechargeable cells: Chemical reactions stop once one of the reactants is used up. The reaction is not reversible.
  • Rechargeable cells: Supplying an external electric current forces electrons in the opposite direction, reversing the chemical reaction so the cell can be used again.

❌ Common Errors

Writing "faster", "stopped", or "started". The mark scheme explicitly notes: ignore "faster".

Topics

Chemistry · C4: Chemical Changes · C5: Energy Changes

Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Foundation), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.