AQA GCSE Combined Science: Trilogy Chemistry Paper 1 (Foundation), 2022: Question 7

6 marks · Standard Demand difficulty · Extended Answer

Plan an investigation to determine the reactivity order of three metals based on their temperature change when reacting with hydrochloric acid.

Practise this question

Question

The image shows a chemistry exam question numbered 07. It asks students to plan an investigation to find the order of reactivity of three metals using the temperature change when each metal reacts with hydrochloric acid. The question is worth 6 marks and provides several lines for a written response.
Question text

07 Plan an investigation to find the order of reactivity of three metals.

You should use the temperature change when each metal reacts with

hydrochloric acid.

[6 marks]

Mark scheme

Show the mark scheme The mark scheme for question 07 uses a level-based marking system. Level 3 (5-6 marks) requires a logically sequenced method leading to a valid outcome. Indicative content includes measuring acid volume into a polystyrene cup, recording initial temperature, adding a fixed mass of metal, stirring, recording the maximum temperature, and calculating the change. It emphasizes control variables like mass and concentration, and notes that the most reactive metal produces the largest temperature change.

Question 7

AO /

Question Answers Mark

Spec. Ref.

07 Level 3: The method would lead to the production of a valid 5–6 AO3

outcome. All key steps are identified and logically sequenced.

Level 2: The method would not necessarily lead to a valid 3–4 AO3

outcome. Most steps are identified, but the method is not fully

logically sequenced.

Level 1: The method would not lead to a valid outcome. Some 1–2 AO1

relevant steps are identified, but links are not made clear.

No relevant content. 0

5.1.4.2

Indicative Content RPA2

• measure volume of (hydrochloric) acid

• into a suitable container eg polystyrene cup

• measure the initial temperature (of hydrochloric acid)

• with a thermometer

• add stated mass of one metal

• stir

• measure the highest temperature reached of the solution

or

measure temperature reached after a set time period

• determine the temperature difference

• repeat

• repeat for each metal

• with same mass

• in same physical state (powder, lump, etc)

• with the same volume and / or concentration of (hydrochloric)

acid

• use results to arrange metals in order of reactivity

• most reactive metal has the largest temperature change

to access level 3 there must be an indication of how the

temperature change is determined with the same mass of the 3

different metals reacted with the same volume of (hydrochloric)

acid

Total Question 7 6

How to answer it

Investigating Metal Reactivity via Temperature Change

What this question tests

This is a Required Practical (RPA 10) question. It assesses your ability to plan a valid scientific investigation, identify variables to keep the test fair, and use experimental data (temperature change) to draw a conclusion about chemical properties (reactivity).

Question 07 (6 Marks)

The Task: Plan an Investigation

You need to describe a step-by-step method to rank three metals from most to least reactive based on how much they heat up when added to acid.

✅ The Perfect Method

  1. Measure a set volume of hydrochloric acid (e.g. 25 cm³) into a polystyrene cup.
  2. Measure and record the initial temperature of the acid using a thermometer.
  3. Add a set mass (e.g. 1g) of the first metal to the acid.
  4. Stir the mixture.
  5. Measure and record the highest temperature reached.
  6. Calculate the temperature change.
  7. Repeat the process for the other two metals using the same volume of acid and mass of metal.

🧠 How to get 6/6 (Level 3)

To reach the top marks, your answer must be logical and valid. This means:

  • You must explicitly state what you are measuring (Initial vs Final temp).
  • You must list Control Variables (same volume of acid, same mass of metal, same surface area/state of metal).
  • You must explain how to use the results: "The metal with the largest temperature increase is the most reactive."

💡 Key Knowledge

  • Exothermic: These reactions release heat energy to the surroundings.
  • Reactivity: A more reactive metal reacts faster and more vigorously, releasing more energy in a shorter time, leading to a higher temperature rise.
  • Insulation: We use a polystyrene cup because it is a good insulator, reducing heat loss to the room so our measurements are more accurate.

❌ Common Errors

  • Vague amounts: Saying "add some acid" instead of "measure a fixed volume."
  • Missing the 'Start': Forgetting to measure the temperature before adding the metal.
  • No Stirring: Forgetting to stir means the heat isn't distributed evenly, leading to inaccurate readings.
  • Equipment: Using a glass beaker instead of a polystyrene cup (loses marks for "validity" because of heat loss).

Processing the Results

📐 Step-by-Step Logic

  1. Calculate Change: Temperature Change = Final (Highest) Temp – Initial Temp.
  2. Compare: Look at the values for Metal A, B, and C.
  3. Rank:
    Highest ΔT = Most Reactive
    Lowest ΔT = Least Reactive
Examiner Tip: If the question asks for a "plan," always imagine you are writing a recipe for someone who has never done the experiment before. If they followed your instructions exactly, would they get the right answer? If yes, you've earned the marks!

Diagram Description

If you were to draw this setup, the examiner would look for:

  • A polystyrene cup sitting inside a glass beaker (for stability).
  • A thermometer submerged in the liquid.
  • A lid on the cup (optional, but shows great technique to reduce heat loss).
  • Labels for the hydrochloric acid and the metal powder/ribbon.

Topics

Chemistry · C4: Chemical Changes · C5: Energy Changes

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Chemistry Paper 1 (Foundation), 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.