AQA GCSE Chemistry Chemistry Paper 2 (Foundation), June 2025: Question 1

10 marks · Low Demand difficulty · Short Answer

Identify ions using flame tests, precipitation reactions with sodium hydroxide, tests for carbonates, sulfates, and halides.

Practise this question

Question

Question 1 on chemical analysis spanning seven parts: 01.1 asks to describe how to carry out a flame test using a metal wire and Bunsen burner (2 marks). 01.2 asks to match lithium and potassium to flame colours chosen from crimson, green, lilac, orange-red, and yellow (2 marks). 01.3 is a multiple choice question asking which gas is produced when carbonates react with dilute acids (1 mark). 01.4 asks which solution is used to test for sulfate ions, with options barium chloride, magnesium chloride, or sodium chloride (1 mark). 01.5 asks to complete a sentence defining a precipitate from gas, liquid, solid (1 mark). 01.6 requires matching copper(II) and magnesium ions to precipitate colours chosen from blue, brown, green, white, and yellow (2 marks). 01.7 asks for the colour of the precipitate formed when nitric acid and silver nitrate are added to iodide ions, choosing from brown, green, and yellow (1 mark).
Question text

01 This question is about chemical analysis.

Some metal ions can be identified using a flame test.

01.1 Describe how to do a flame test using a metal wire and a Bunsen burner.

[2 marks]

01.2 Draw one line from each metal ion to the flame colour produced by the metal ion.

[2 marks]

Metal ion Flame colour

Crimson

Green

Lithium

Lilac

Potassium

Orange-red

3 Yellow

01.3 Which gas is produced when carbonates are reacted with dilute acids?

[1 mark]

Tick ( ) one box.

Carbon dioxide

Hydrogen

Oxygen

01.4 Which solution is used to test for sulfate ions?

[1 mark]

Tick ( ) one box.

Barium chloride solution

Magnesium chloride solution

Sodium chloride solution

Precipitates are used to identify some ions.

01.5 Complete the sentence.

Choose the answer from the box.

[1 mark]

gas liquid solid

A precipitate is a 4 .

01.6 Some metal ions in solution can be identified by adding sodium hydroxide solution.

Draw one line from each metal ion to the colour of the precipitate produced

by the metal ion.

*03* [2 marks]

Metal ion Colour of precipitate

Blue

Brown

Copper(II)

Green

Magnesium

White

Yellow

01.7 Dilute nitric acid and silver nitrate solution were added to a solution containing

iodide ions.

Complete the sentence.

Choose the answer from the box.

[1 mark]

brown green yellow

The colour of the precipitate produced is .

Mark scheme

Show the mark scheme Mark scheme for Question 1: 01.1 awards 1 mark for putting the sample on the wire and 1 mark for holding the wire in a blue/non-luminous flame. 01.2 shows lithium linked to crimson and potassium linked to lilac (1 mark each). 01.3 accepts carbon dioxide (1 mark). 01.4 accepts barium chloride solution (1 mark). 01.5 accepts solid (1 mark). 01.6 shows copper(II) linked to blue and magnesium linked to white (1 mark each). 01.7 accepts yellow (1 mark). Total: 10 marks.

Question 1

AO /

Question Answers Extra information Mark

Spec. Ref.

01.1 put sample on (metal) wire ignore references to cleaning 1 AO1

4.8.3.1

hold wire in (blue / non- 1 RPA7

luminous) flame

AO /

Question Answers Mark

Spec. Ref.

01.2 AO1

4.8.3.1

RPA7

do not accept more than one line from a box on the left

AO /

Spec. Ref.

01.3 carbon dioxide 1 AO1

4.8.3.3

AO /

Spec. Ref.

01.4 barium chloride solution 1 AO1

4.8.3.5

RPA7

AO /

Spec. Ref.

01.5 solid 1 AO1 7

4.2.2.1

4.8.3.5

AO /

Spec. Ref.

01.6 AO1

4.8.3.2

RPA7

do not accept more than one line from a box on the left

AO /

Spec. Ref.

01.7 yellow 1 AO1

4.8.3.4

Total Question 1 10

How to answer it

Chemical Analysis: Tests for Ions

📋 What This Question Tests

This question assesses core recall from Required Practical 7 (Identifying Ions) and specification topic 4.8 Chemical Analysis:

  • Flame test experimental method and characteristic flame colours (Li⁺, K⁺).
  • Testing for negative ions (anions): carbonates (CO₃²⁻), sulfates (SO₄²⁻), and halides (I⁻).
  • Identifying positive ions (cations) using sodium hydroxide precipitate tests (Cu²⁺, Mg²⁺).
  • Understanding key chemical vocabulary (definition of a precipitate).

Question 01.1: Flame Test Method

Describing how to perform a flame test using wire and a Bunsen burner [2 marks]

✅ Mark Scheme Model Answer

  1. Put sample on the (metal/nichrome) wire [1 mark]
  2. Hold the wire in a blue / non-luminous flame [1 mark]

🧠 Exam Technique

Always state the flame type! Simply saying "put it in the Bunsen flame" loses the second mark. The flame must be specified as blue, roaring, or non-luminous so the flame's own colour doesn't obscure the sample.

❌ Common Pitfalls

  • Vague descriptions: "Burn the sample" or "heat the chemical" does not describe the physical action of putting it on the wire.
  • Irrelevant steps: While dipping wire in concentrated HCl to clean it is good lab practice, the mark scheme specifically notes: "ignore references to cleaning"—don't waste writing time on cleaning when only the basic method is asked.

Question 01.2: Flame Test Colours

Matching metal ions to flame colours [2 marks]

✅ Correct Pairings

  • Lithium → Crimson [1 mark]
  • Potassium → Lilac [1 mark]

💡 GCSE Flame Colours Recall

  • Lithium (Li⁺): Crimson
  • Sodium (Na⁺): Yellow
  • Potassium (K⁺): Lilac
  • Calcium (Ca²⁺): Orange-red
  • Copper (Cu²⁺): Green
⚠️ Examiner Rule: "Do not accept more than one line from a box on the left." Drawing multiple lines from one ion gives zero marks for that pair.

Question 01.3: Carbonate Reaction

Gas produced when carbonates react with dilute acids [1 mark]

✅ Correct Selection

☑ Carbon dioxide [1 mark]

💡 General Reaction Rule

Acid + Metal Carbonate → Salt + Water + Carbon Dioxide

Carbon dioxide turns limewater cloudy/milky when bubbled through it.

Question 01.4: Sulfate Ion Test

Identifying the correct reagent for sulfate ions [1 mark]

✅ Correct Selection

☑ Barium chloride solution [1 mark]

🧠 Why Barium?

When barium chloride solution is added in the presence of dilute hydrochloric acid (HCl), barium ions react with sulfate ions to form an insoluble white precipitate:

Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)

Question 01.5: Definition of a Precipitate

Completing the definition sentence [1 mark]

✅ Sentence Completion

A precipitate is a solid. [1 mark]

💡 Scientific Meaning

A precipitate is an insoluble solid that forms when two aqueous solutions react together. Look for state symbol (s) in precipitation equations.

Question 01.6: Sodium Hydroxide Tests

Matching metal ions to hydroxide precipitate colours [2 marks]

✅ Correct Pairings

  • Copper(II) → Blue [1 mark]
  • Magnesium → White [1 mark]

💡 Precipitates with NaOH (aq)

  • Copper(II), Cu²⁺: Blue precipitate, Cu(OH)₂
  • Iron(II), Fe²⁺: Green precipitate, Fe(OH)₂
  • Iron(III), Fe³⁺: Brown precipitate, Fe(OH)₃
  • Magnesium, Mg²⁺: White precipitate, Mg(OH)₂ (does not dissolve in excess NaOH)

Question 01.7: Halide Test for Iodide

Precipitate colour with nitric acid and silver nitrate [1 mark]

✅ Sentence Completion

The colour of the precipitate produced is yellow. [1 mark]

💡 The Silver Halide Precipitate Trio

  • Chloride (Cl⁻): White precipitate (AgCl)
  • Bromide (Br⁻): Cream precipitate (AgBr)
  • Iodide (I⁻): Yellow precipitate (AgI)

Memory hook: "Cats Can't Yawn" → Chloride (White), Bromide (Cream), Iodide (Yellow).

❌ Common Misconceptions

Students often mix up silver halide precipitates (white, cream, yellow) with transition metal hydroxide precipitates (blue, green, brown). Take time to memorize them as two distinct lists!

Topics

Chemistry · Required Practicals · C8: Chemical Analysis · Required Practicals

Question and mark scheme from the AQA GCSE Chemistry examination, Chemistry Paper 2 (Foundation), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.