AQA GCSE Chemistry Chemistry Paper 1 (Higher), 2023: Question 3

8 marks · Standard Demand difficulty · Extended Answer

Describe a method to prepare pure, dry crystals of zinc chloride from zinc carbonate and a dilute acid, and identify two other substances that can react with a dilute acid to form zinc chloride.

Practise this question

Question

The image shows two sub-questions. Question 03.1 asks for a 6-mark plan to make pure, dry crystals of zinc chloride from zinc carbonate and a dilute acid. Question 03.2 asks to name two other substances that can react with a dilute acid to make zinc chloride, excluding zinc carbonate.
Question text

03 This question is about making a soluble salt.

03.1 Plan a method to make pure, dry crystals of zinc chloride from zinc carbonate and a

dilute acid.

[6 marks]

03.2 Name two other substances that can each be reacted with a dilute acid to make

zinc chloride.

Do not refer to zinc carbonate in your answer.

[2 marks]

Mark scheme

Show the mark scheme The mark scheme provides a level-based marking criteria for 03.1, detailing the steps: adding zinc carbonate to hydrochloric acid until in excess, filtering the mixture, heating the solution to crystallisation point, and drying the crystals. For 03.2, it lists zinc, zinc oxide, and zinc hydroxide as the correct answers.

AO/

Question Answers Mark

Spec. Ref

Level 3: The method would lead to the production of a valid AO1

03.1 5–6

outcome. The key steps are identified and logically sequenced. 4.4.2.2

4.4.2.3

Level 2: The method would not necessarily lead to a valid RPA1

outcome. Most steps are identified, but the method is not fully 3–4

logically sequenced.

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

1–2

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

No relevant content 0

Indicative content

• use zinc carbonate and hydrochloric acid

• add zinc carbonate to the (hydrochloric) acid

• in a beaker

• stir

• continue adding until the zinc carbonate is in excess

• shown by excess solid

• and no more effervescence

• filter (the reaction mixture)

• to remove the excess zinc carbonate

• heat the solution

• using a water bath or electric heater

• to crystallisation point

• leave the solution to crystallise

• pat crystals dry with filter paper

AO /

Question Answers Extra information Mark

Spec. Ref.

03.2 any two from: 2 AO2

• zinc allow Zn 4.4.2.3

• zinc oxide allow ZnO

• zinc hydroxide allow Zn(OH)2

– HEMISTRY – –

Total Question 3 8

Question 4

How to answer it

Making Soluble Salts: Zinc Chloride

What this question tests

This question assesses your knowledge of Required Practical 1 (RPA1). You need to know how to react an acid with an insoluble base to form a salt, how to ensure the reaction is complete, and how to safely crystallise the product to get pure, dry crystals.

Part (03.1)

Planning a Method for Salt Preparation

6 Marks - Extended Writing

💡 Key Knowledge

  • To make a chloride salt, you must use hydrochloric acid (HCl).
  • Zinc Carbonate + Hydrochloric Acid → Zinc Chloride + Water + Carbon Dioxide
  • ZnCO₃ + 2HCl → ZnCl₂ + H₂O + CO₂

🧠 Exam Technique

For a 6-mark "Plan a method" question, the examiner looks for a logical sequence. Use bullet points to ensure you don't skip steps like filtering or drying.

✅ The Perfect Method

  1. Pour a fixed volume of hydrochloric acid into a beaker.
  2. Add zinc carbonate one spatula at a time and stir.
  3. Continue adding until the zinc carbonate is in excess (this is shown when solid remains at the bottom and no more fizzing occurs).
  4. Filter the mixture using a funnel and filter paper to remove the unreacted zinc carbonate.
  5. Pour the filtrate into an evaporating dish and heat gently (using a water bath or electric heater) to the crystallisation point.
  6. Leave the solution to cool and crystallise.
  7. Remove the crystals and pat dry with filter paper.

❌ Common Errors & Examiner Tips

  • Wrong Acid: Many students forget to name the acid. If you use sulfuric acid, you make zinc sulfate, not zinc chloride!
  • Evaporating to Dryness: Do NOT say "heat until all the water has gone." This produces a powder. To get crystals, you must stop heating at the "crystallisation point" (when crystals start to form on a glass rod).
  • Missing the "Pure" part: If you don't filter the excess solid out, your salt won't be pure.
Part (03.2)

Alternative Reactants

2 Marks

💡 Key Knowledge

To make the salt Zinc Chloride, you always need Hydrochloric Acid, but you can swap the Zinc Carbonate for other zinc-containing substances:

  • Zinc (metal) + Acid → Salt + Hydrogen
  • Zinc Oxide (base) + Acid → Salt + Water
  • Zinc Hydroxide (alkali) + Acid → Salt + Water

✅ Correct Answers (Pick Two)

  • Zinc
  • Zinc oxide
  • Zinc hydroxide

Note: Chemical symbols (Zn, ZnO, Zn(OH)₂) are also accepted.

🧠 Examiner Insight

Read the question carefully! It says "Do not refer to zinc carbonate." If you list it again, you will lose a mark. This part tests your ability to recall the general reactions of acids.

Visualising the Setup

📐 What to Draw (if asked)

If you were asked to diagram this, you should show:

  • Filtration: A conical flask with a filter funnel and paper containing "excess solid."
  • Crystallisation: An evaporating basin sitting on top of a beaker of boiling water (a water bath) to show gentle heating.

Topics

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

Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 1 (Higher), 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.