AQA GCSE Chemistry Chemistry Paper 1 (Higher), 2024: Question 1

10 marks · Standard Demand difficulty · Short Answer

A series of questions regarding the preparation of copper sulfate from copper carbonate and sulfuric acid, including word equations, practical observations, equipment, percentage yield calculations, and reactivity trends.

Practise this question

Question

A multi-part chemistry exam question about preparing copper sulfate. It includes a numbered method list (1-7), followed by sub-questions 01.1 to 01.6 asking for a word equation, observations, equipment, a percentage yield calculation, and reasons why copper and sodium are not used in this reaction.
Question text

01 A student produced a salt by reacting copper carbonate with sulfuric acid.

This is the method used.

1. Measure 50 cm3 of sulfuric acid into a beaker.

2. Add copper carbonate powder.

3. Stir the mixture.

4. Repeat steps 2 and 3 until copper carbonate is in excess.

5. Filter the mixture.

6. Warm the filtrate gently until crystals start to appear.

7. Leave the solution to cool and crystallise.

01.1 Complete the word equation for the reaction.

[2 marks]

copper sulfuric carbon

+ → + +

carbonate acid dioxide

01.2 Give one observation the student could make during Step 4 which shows that the

copper carbonate is in excess.

[1 mark]

01.3 Give one reason for filtering the mixture in Step 5.

[1 mark]

01.4 Name the equipment that can be used to warm the filtrate gently in Step 6.

[1 mark]

*0021.*5 The maximum theoretical mass of the salt that could be produced using 50 cm3 of the

sulfuric acid is 12.5 g.

The percentage yield of the salt is 92.8%.

Calculate the mass of salt actually produced.

Use the equation:

mass of salt actually produced

% yield = ×100

maximum theoretical mass of salt that could be produced

[3 marks]

4 Mass of salt actually produced = g

01.6 Some salts can be produced by reacting sulfuric acid with a metal.

Neither copper nor sodium is used to produce a salt with sulfuric acid.

Give one reason why each metal is not used.

[2 marks]

Copper

Sodium

Mark scheme

Show the mark scheme A table showing the mark scheme for question 1. It lists the required answers for each sub-question (01.1 to 01.6), including specific chemical names, observations, equipment, the calculation steps for percentage yield, and explanations regarding metal reactivity.

Question 1

AO /

Question Answers Extra information Mark

Spec. Ref.

01.1 copper sulfate allow CuSO4 1 AO2

water allow H2O 1 AO1

4.4.2.2

4.4.2.3

RPA1

AO /

Spec. Ref.

01.2 ignore references to colours AO1

4.4.2.3

solid remains (in the mixture) allow copper carbonate remains 1 RPA1

(in the mixture)

or

no more effervescence /

bubbles / fizzing

AO /

Spec. Ref.

01.3 to remove copper carbonate allow to remove excess (copper 1 AO1

carbonate) 4.1.1.2

4.4.2.3

RPA1

AO /

Spec. Ref.

01.4 electric heater ignore Bunsen burner 1 AO1

or 4.4.2.3

water bath – – – RPA1

AO /

Spec. Ref.

01.5 mass produced allow 1 AO2

92.8 = × 100 mass produced = 4.3.3.1

12.5

max theoretical mass

% yield ×

92.8 7

(mass produced) = × 12.5 1

= 11.6 (g) 1

AO /

Spec. Ref.

01.6 (copper) AO1

does not react with (sulfuric) allow is unreactive 1

acid allow will not displace hydrogen

allow is below hydrogen in the

reactivity series AO3

ignore is not reactive enough 4.4.1.2

4.4.2.3

(sodium)

could explode allow (the reaction is) dangerous 1

or

could get too hot

Total Question 1 10

How to answer it

Making Soluble Salts & Yield Calculations

What this question tests

This question focuses on Required Practical 1 (RPA1): preparing a pure, dry sample of a soluble salt from an insoluble oxide or carbonate. It assesses your knowledge of chemical equations, experimental observations, separation techniques (filtration and crystallisation), percentage yield calculations, and the reactivity series.

Part 01.1: Completing the Equation

💡 Key Knowledge

When a metal carbonate reacts with an acid, the products are always:

  • A Salt
  • Water
  • Carbon Dioxide

✅ Correct Answer

copper carbonate + sulfuric acid → copper sulfate + water + carbon dioxide

1 mark for copper sulfate, 1 mark for water.

🧠 Exam Technique

To name the salt: The first part comes from the metal (copper). The second part comes from the acid (sulfuric acid makes sulfates).

Parts 01.2 & 01.3: Observations and Filtration

Identifying "Excess" and Separating Mixtures

✅ Correct Answers

01.2: Solid remains in the mixture OR no more fizzing/bubbles.

01.3: To remove the unreacted/excess copper carbonate.

🧠 Exam Technique

In Step 4, we add the powder until it is in excess. This ensures all the acid has reacted. You know it's in excess when you see solid sitting at the bottom that won't disappear even after stirring.

❌ Common Errors

  • 01.2: Don't just say "it changes colour." You must describe a physical observation that proves the reaction has stopped.
  • 01.3: Students often say "to get the salt." This is too vague. You filter to remove the excess solid so you are left with a pure solution of the salt.

Part 01.4: Crystallisation Equipment

💡 Key Knowledge

Step 6 asks for gentle warming. Using a Bunsen burner directly can sometimes be too harsh and cause the salt to decompose or spit (decrepitation).

✅ Correct Answer

Electric heater or water bath.

1 mark. Note: Examiners usually ignore "Bunsen burner" if the question specifies "gentle."

Part 01.5: Percentage Yield Calculation

📐 Step-by-Step Calculation

1. Identify the values:
% Yield = 92.8%
Theoretical Mass = 12.5 g

2. Rearrange the formula:
Actual Mass = (% Yield × Theoretical Mass) / 100

3. Substitute and solve:
Actual Mass = (92.8 × 12.5) / 100
Actual Mass = 1160 / 100
Actual Mass = 11.6 g

🧠 Exam Technique

Always check if your answer makes sense. The "actual" mass must be less than the "theoretical" mass (12.5 g). If your answer is 11.6 g, it fits!

Part 01.6: Reactivity and Metal Choice

💡 Key Knowledge

We don't use Copper metal because it is below hydrogen in the reactivity series; it won't react with dilute acids.

We don't use Sodium metal because it is in Group 1; it is far too reactive and the reaction would be explosive/dangerous.

✅ Correct Answer

Copper: Does not react with (sulfuric) acid / unreactive.

Sodium: Reaction is too violent / explosive / dangerous.

1 mark for each correct reason.

❌ Common Errors

Avoid saying copper is "not reactive enough." Use the specific term unreactive or state it is below hydrogen in the reactivity series. For sodium, avoid saying "it's too fast"—use dangerous or explosive.

Visual Summary: Required Practical 1

If asked to draw the apparatus for Step 5 and 6, remember:

  • Filtration: A funnel with filter paper sitting in a conical flask. Label the "excess copper carbonate" in the paper and "copper sulfate solution" in the flask.
  • Crystallisation: An evaporating basin sitting on a tripod and gauze (or over a beaker of water for a water bath).

Topics

Chemistry · Required Practicals · C4: Chemical Changes · C3: Quantitative Chemistry · Required Practicals

Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Higher), 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.