AQA GCSE Combined Science: Trilogy Chemistry Paper 1 (Foundation), 2020: Question 2

11 marks · Standard Demand difficulty · Short Answer

Investigate temperature change when different metals are added to copper sulfate solution, interpret a thermometer reading and reactivity series, and calculate a scaled mass from concentration data.

Practise this question

Question

The page shows a chemistry investigation about adding different metals to copper sulfate solution and measuring the temperature change. It includes a method in four steps, a diagram of a beaker containing copper sulfate solution, metal X, and a thermometer, and a close-up thermometer reading at the start of the investigation. The questions ask for the temperature change, two control variables, the mean temperature change from a table of four test results with one anomalous result, reasoning from a reactivity series diagram, a multiple-choice question about adding silver, an explanation of why potassium should not be added, and a proportional calculation using 100 cm³ of solution containing 1.8 g of copper sulfate.
Question text

02 A student investigated the temperature change when metal X was added to

copper sulfate solution.

This is the method used.

1. Add 25 cm3 of copper sulfate solution to a beaker.

2. Measure the temperature of the copper sulfate solution.

3. Add 1.0 g of metal X and stir.

4. Measure the highest temperature reached when metal X is added to

copper sulfate solution.

5. Repeat steps 1 to 4 with different metals.

Figure 1 shows the apparatus used.

Figure 1

Figure 2 shows the thermometer reading of the copper sulfate solution at the start of

the investigation.

Figure 2

02.1 The highest temperature reached when metal X was added to copper sulfate solution

was 35.5 °C

*06* Determine the temperature change when metal X is added to copper sulfate solution.

Use Figure 2.

[2 marks]

Highest temperature = 35.5 °C

Temperature at start = °C

Temperature change = °C

02.2 Give two variables the student should keep the same in this investigation.

[2 marks]

02.3 The student repeated the experiment with metal Y.

Table 1 shows four results for metal Y.

Table 1

Test 1 Test 2 Test 3 Test 4

Temperature change in °C 9.2 7.3 9.5 9.2

Calculate the mean temperature change for metal Y.

Do not include the anomalous result in your calculation.

[2 marks]

Mean temperature change = °C

The more reactive the metal added to copper sulfate solution, the greater the

temperature change.

*07* Figure 3 shows a reactivity series.

Figure 3

Potassium most reactive

Calcium

Magnesium

Zinc

Copper

Silver least reactive

02.4 The student repeated the experiment.

The student added:

• magnesium to copper sulfate solution

• an unknown metal A to copper sulfate solution.

Table 2 shows the results.

Table 2

Metal Temperature change in °C

Magnesium 12

Metal A 8

The student concludes metal A is zinc.

Give one reason why the student is correct.

Use Figure 3 and Table 2.

[1 mark]

02.5 The student did the experiment with silver and copper sulfate solution.

What happens to the temperature of the mixture?

*08* Use Figure 3.

[1 mark]

Tick ( ) one box.

Decreases

Increases

Stays the same

02.6 Suggest one reason why the student should not add potassium metal to

copper sulfate solution.

[1 mark]

02.7 100 cm3 of the copper sulfate solution contains 1.8 g of copper sulfate.

Calculate the mass of copper sulfate in 25 cm3 of this copper sulfate solution.

[2 marks]

Mass = g

Mark scheme

Show the mark scheme The mark scheme lists answers for questions 02.1 to 02.7. It gives the start temperature as 21.1 °C, accepts 14.4 °C if a different correct start reading is used, and awards marks for naming two control variables such as surface area, volume of copper sulfate solution, concentration, and mass of metal. It shows the mean temperature change for metal Y as 9.3 °C after excluding the anomalous result, states that metal A or zinc is less reactive than magnesium or lower in the reactivity series, says silver causes no temperature increase, explains potassium is too dangerous or too reactive because it would react with water, and calculates the final mass as 0.45 g using 25/100 × 1.8.

AO /

Question Answers Extra information Mark

Spec. Ref.

02.1 21.1 (°C) 1 AO2

5.4.1.2

14.4 (°C) allow correct use of an incorrect 1 5.5.1.1

start temperature RPA 10

02.2 any two from: 2 AO2

5.4.1.2

• surface area of metal 5.5.1.1

• 25 cm3 / volume of copper RPA 10

sulfate solution

• concentration of

copper sulfate solution

• mass / 1 g of metal

ignore amount

ignore temperature

ignore stirring

02.3

9.2 + 9.5 + 9.2 27.9

or 1 AO3

= 9.3 (°C) 1 AO2

if no other mark awarded allow

1 mark for 8.8 (°C) 5.4.1.2

5.5.1.1

RPA 10

02.4 (metal A / zinc) is less reactive allow converse 1 AO3

(than magnesium) 5.4.1.2

or 5.5.1.1

(metal A / zinc) is lower in RPA 10

reactivity series

or

change in temperature is lower

(with metal A / zinc)

02.5 stays the same 1 AO3

5.4.1.2

5.5.1.1

RPA 10

02.6 too dangerous 1 AO2

or 5.1.2.5

too reactive 5.4.1.2

allow potassium would react 5.5.1.1

with water (RPA 10)

02.7 25 1

× 1.8 or × 1.8 1 AO2

100 4 5.3.2.5

RPA 10

= 0.45 (g) 1

Total 11

How to answer it

Standard Demand

Investigating Metal Reactivity

What this question tests: This question assesses your ability to interpret experimental data, perform basic calculations (means and proportions), and apply knowledge of the reactivity series to predict chemical outcomes. It focuses on Required Practical Activity (RPA) 10.

Part 02.1: Reading Data

Answer: Start temperature = 21.1 °C; Temperature change = 14.4 °C.
Exam Technique: When reading a thermometer, look directly at the meniscus (the bottom of the curve). Each small line represents 0.1 °C. Always double-check your subtraction: 35.5 - 21.1 = 14.4.

Part 02.2: Control Variables

Key Knowledge: To make an experiment "fair," you must keep variables constant. Acceptable answers include:
  • Volume of copper sulfate solution (25 cm³)
  • Concentration of copper sulfate solution
  • Mass of the metal (1.0 g)
  • Surface area of the metal

Part 02.3: Calculating the Mean

Step-by-Step Calculation:
  1. Identify the anomaly: Look for the result that doesn't fit the pattern. 7.3 is significantly lower than the others. Exclude it.
  2. Sum the valid results: 9.2 + 9.5 + 9.2 = 27.9
  3. Divide by the count: 27.9 / 3 = 9.3 °C
Common Error: Including the anomalous result (7.3) in your calculation will lose you the accuracy mark. Always check for outliers before calculating a mean.

Part 02.4: Interpreting Reactivity

Answer: Metal A is lower in the reactivity series than magnesium, resulting in a smaller temperature change.
Examiner Commentary: You must explicitly link the data (Table 2) to the theory (Figure 3). Simply saying "it is less reactive" is good, but explaining *why* (the temperature change is lower) ensures you secure the mark.

Part 02.5: Predicting Outcomes

Answer: Stays the same.
Key Knowledge: Silver is below copper in the reactivity series. Because silver is less reactive than copper, it cannot displace copper from the copper sulfate solution. No reaction occurs, so no heat is released.

Part 02.6: Safety Considerations

Answer: Potassium is too reactive / dangerous.
Key Knowledge: Potassium reacts violently with water (which is present in the solution), potentially causing an explosion or fire.

Part 02.7: Proportional Calculation

Step-by-Step Calculation:
  1. Find the ratio: You are using 25 cm³ instead of 100 cm³. 25 / 100 = 0.25 (or 1/4).
  2. Apply the ratio: 0.25 × 1.8 g = 0.45 g.
Common Error: Don't overcomplicate the math. If the volume is divided by 4, the mass of the solute must also be divided by 4. Keep your units (g) consistent.

Topics

Chemistry · C4: Chemical Changes · C3: Quantitative Chemistry

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Chemistry Paper 1 (Foundation), 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.