AQA GCSE Combined Science: Trilogy Chemistry Paper 1 (Higher), 2022: Question 3

Mark scheme

Show the mark scheme

Question 3

AO /

Question Answers Mark

Spec. Ref.

03 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 3 6

How to answer it

AQA GCSE Combined Science: Trilogy · Required Practical style planning question

Investigating metal reactivity using temperature change

What this question tests Planning a fair test, measuring temperature change accurately, controlling variables, and using results to rank metals by reactivity. You need to show a clear method, use the same acid conditions for each metal, and explain that the most reactive metal gives the biggest temperature rise.

Overall skill: AO3 planning an investigation so the results are valid and can be compared fairly.

Question

Plan an investigation to find the order of reactivity of three metals using the temperature change when each metal reacts with hydrochloric acid.

Marks available: 6

Part (a) — How to plan the investigation

What a full-mark answer should include

✅ Correct answer points

Measure a fixed volume of hydrochloric acid.
Put the acid into a suitable container, such as a polystyrene cup.
Measure the initial temperature of the acid using a thermometer.
Add a known mass of one metal to the acid.
Stir the mixture.
Measure the highest temperature reached, or measure the temperature after a fixed time.
Work out the temperature change: final temperature − initial temperature.
Repeat for each of the three metals.
Keep the mass, physical form, and acid volume/concentration the same each time.
Use the results to rank the metals; the biggest temperature change means the most reactive metal.

💡 Key knowledge

More reactive metals react faster and release more heat in this type of test.
Temperature rise shows how energetic the reaction is.
A polystyrene cup helps reduce heat loss, so results are more accurate.
Using the same mass of each metal makes the comparison fair.
Using the same acid concentration and volume stops the acid amount changing the result.

🧠 Exam technique

Write the method in a logical order: measure → mix → record → compare.
Be specific: say “same volume”, “same concentration”, “same mass”.
To reach top level, make clear how the temperature change is found for all three metals.
Link the result to reactivity: largest temperature change = most reactive.

Part (a) — Model full-mark response

✅ Example answer

Measure the same volume of hydrochloric acid into a polystyrene cup. Record the initial temperature with a thermometer. Add the same mass of the first metal, stir, and measure the highest temperature reached. Calculate the temperature change by subtracting the initial temperature from the highest temperature. Repeat the test for the other two metals using the same volume and concentration of acid, and the same mass and physical form of metal. Compare the temperature changes. The metal that gives the largest temperature rise is the most reactive.

How marks are awarded

💡 Level 3 response

All key steps are included.
The method is logically sequenced.
It would produce a valid outcome.
It clearly explains how to compare all three metals fairly.

Likely mark: 5–6

🧠 What separated top answers

They stated that the same mass of each of the 3 metals must be used.
They stated that the same volume of hydrochloric acid must be used.
They clearly described how the temperature change is measured.
They used the temperature change to rank the metals in order of reactivity.

❌ Common errors

Only saying “measure temperature” without saying initial and highest/final temperature.
Forgetting to repeat the test for all three metals.
Not controlling the mass of the metal.
Not controlling the acid volume or concentration.
Saying “the hottest metal” instead of explaining the largest temperature change.

Part (a) — Why these details matter

📐 Temperature change method

Measure the initial temperature of the acid.
Add the metal and stir.
Measure the highest temperature reached.
Calculate: temperature change = highest temperature − initial temperature

💡 Fair test variables

Independent variable: the metal used.
Dependent variable: temperature change.
Control variables: mass of metal, volume of acid, concentration of acid, same container, same physical form of metal, same stirring/time.

🧠 Examiner tip

If you want full marks, make sure your answer sounds like a real method, not just a list of facts. The examiner is looking for a test that could be done and compared fairly.

Part (a) — Common misconceptions

❌ What students often got wrong

Not stating how the temperature change is obtained.
Using different masses of metal and then trying to compare the results.
Ignoring the need to repeat the investigation for each metal.
Thinking the biggest final temperature alone is enough, rather than the change in temperature.
Not saying that the most reactive metal gives the largest temperature change.

Quick revision answer

✅ 6-mark checklist

Same volume of hydrochloric acid
Same concentration of hydrochloric acid
Polystyrene cup or other suitable container
Measure initial temperature
Add same mass of each metal, stir, measure highest/final temperature
Calculate temperature change and compare the results to rank reactivity

Topics

Chemistry · Required Practicals · C4: Chemical Changes · Chemistry Required Practicals