plumiFlame colours and thermal decomposition experiments: Edexcel International A Level Chemistry questions
Edexcel International A Level Chemistry past-paper questions on 8.B.4 Flame colours and thermal decomposition experiments, 2019–2025, with mark schemes and examiner’s reports where available.
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All 51 questions on Flame colours and thermal decomposition experiments, as a list
- June 2025, AS Unit 2, Q7 (1 mark): Which electron movement causes the yellow colour produced in a sodium chloride flame test? A addition of an electron to a sodium ion B an electron moving from a
- June 2025, AS Unit 3, Q2(a)(i) (2 marks): Describe how to carry out a flame test. (2)
- June 2025, AS Unit 3, Q2(a)(ii) (2 marks): The flame test colours for the potassium ion and the rubidium ion are difficult to tell apart. Give the flame test colours for the potassium ion and for the rub
- June 2025, AS Unit 3, Q2(a)(iv) (2 marks): In school laboratories, wooden splints are sometimes used in the flame test instead of the unreactive metal wires. Give one advantage and one disadvantage of us
- January 2025, AS Unit 2, Q4 (1 mark): What is the flame colour produced by strontium ions? A green B red C white D yellow
- January 2025, AS Unit 3, Q1(a)(i) (4 marks): Describe how the student could use flame colour to confirm that the solid sample contains potassium ions. Outline the experimental procedure, stating the colour
- October 2024, AS Unit 2, Q4 (1 mark): Which statement about Group 2 elements and their compounds is true? A calcium hydroxide is less soluble than magnesium hydroxide in water B all Group 2 metals g
- October 2024, AS Unit 2, Q5 (1 mark): A compound, which is a white solid, gives a red flame test and produces a colourless, acidic gas when heated. What is the identity of the compound? A calcium ca
- October 2024, AS Unit 2, Q6 (1 mark): Which statement explains the origin of a flame test colour? A electrons absorb energy as they jump to a higher energy level B electrons emit energy as they jump
- October 2024, AS Unit 3, Q1(b)(i) (4 marks): Describe in outline an experiment to compare the thermal stability of Group 2 carbonates. You may wish to include a diagram. (4)
- October 2024, AS Unit 3, Q1(b)(ii) (1 mark): Give a reason why the experiment described in (b)(i) may not produce the expected results for all the Group 2 carbonates in a school laboratory. (1)
- October 2024, Unit 6, Q1(a)(ii) (1 mark): A green flame was seen when a flame test was carried out on a sample of solid P. Identify P by name or formula. (1) P
- June 2024, AS Unit 2, Q7 (1 mark): Group 2 compounds give different colours in a flame test. The best explanation is that the cations have different A gaps between electronic energy levels B ioni
- June 2024, AS Unit 2, Q8 (1 mark): Two tests were performed on an unknown ionic compound. Silver nitrate solution was added to an aqueous solution of the compound, forming a white precipitate. A
- June 2024 (R), AS Unit 2, Q13 (1 mark): Compound X gives a red flame test and a solution of X produces a white precipitate when added to nitric acid and silver nitrate solution. Which could be compoun
- June 2024 (R), AS Unit 3, Q2(b)(iv) (2 marks): State the colours produced by the magnesium ions and barium ions in a flame test. (2) Magnesium Barium
- January 2024, AS Unit 2, Q21(b)(iii) (1 mark): State the expected flame colour when CaCl2 is used in a flame test. (1)
- January 2024, AS Unit 2, Q21(c)(i) (2 marks): State two observations that would be made. (2) 1 2
- October 2023, AS Unit 3, Q1(a)(i) (3 marks): Describe the method for carrying out a flame test. (3)
- October 2023, AS Unit 3, Q1(a)(ii) (2 marks): Complete the table of results. (2) Formula of Compound Flame colour cation present A Na+ K+ B C pale green
- June 2023, AS Unit 2, Q13 (1 mark): When solid sodium chloride is placed in a Bunsen flame, a persistent yellow colour is observed. The yellow colour is due to A electrons being excited to higher
- June 2023, AS Unit 3, Q1(a)(i) (1 mark): A flame test was carried out on solid A and a pale green colour was observed. Identify, by name or formula, the cation present in A. (1)
- January 2023, AS Unit 2, Q9 (1 mark): Compound Q produces • a red colour in a flame test • a white precipitate when aqueous potassium sulfate is added to a solution of the compound. What is compound
- January 2023, AS Unit 2, Q21 (6 marks): *21 Discuss some aspects of the thermal stability of the anhydrous nitrates of the elements in Groups 1 and 2 of the Periodic Table. In your answer you should e
- January 2023, AS Unit 3, Q1(b) (2 marks): Q is a Group 1 halide which produces a lilac colour in a flame test. When a few drops of dilute nitric acid and aqueous silver nitrate are added to a solution o
- October 2022, AS Unit 2, Q8 (1 mark): What produces the colour in a flame test? Energy change of electrons Movement of electrons A energy absorbed from ground state to excited state B energy emitted
- October 2022, AS Unit 3, Q1(b)(i) (3 marks): State the test you would carry out on separate solid samples of sodium bromide and barium chloride to show the cations present. Include the positive result for
- June 2022, AS Unit 3, Q2(c)(i) (2 marks): State the test the students might use on the white solid to show that M was potassium. Include the expected result. (2)
- October 2021, AS Unit 2, Q21(a)(iii) (1 mark): The reaction of potassium with water is very vigorous and a flame is seen. State the colour of the flame. (1)
- October 2021, AS Unit 3, Q1(a) (2 marks): State a test for the strontium cation, giving the expected result. (2)
- October 2021, AS Unit 3, Q1(c) (1 mark): Anhydrous strontium sulfate undergoes thermal decomposition at approximately 1300 °C. SrSO4(s) → SrO(s) + SO2(g) + ½O2(g) Suggest why this decomposition is unli
- October 2021, AS Unit 3, Q1(d)(i) (1 mark): Describe how to ensure the strontium nitrate decomposes fully. (1)
- October 2021, AS Unit 3, Q1(d)(ii) (1 mark): State the colour of nitrogen dioxide gas. (1)
- October 2021, AS Unit 3, Q1(d)(iii) (1 mark): Give the test for oxygen and the expected positive result. (1)
- June 2021, AS Unit 3, Q1(a)(i) (2 marks): Identify a material from which the flame test wire could be made. Justify your answer. (2)
- June 2021, AS Unit 3, Q1(a)(ii) (4 marks): Describe how to carry out a flame test on a solid, giving the expected flame colour for each of these compounds. (4)
- January 2021, AS Unit 2, Q9 (1 mark): Which of these compounds does not produce a colour in a flame test, and produces an alkaline gas when warmed with sodium hydroxide solution? A Ca(OH)2 B Mg(OH)2
- January 2021, AS Unit 3, Q1(b) (3 marks): Three of the cations in the compounds in (a) can be identified using flame tests. Complete Table 2. (3) Cation formula Flame colour Table 2
- January 2021, AS Unit 3, Q3(a) (1 mark): Give a reason why the delivery tube must be removed from the water bath before removing the test tube from the heat source. (1)
- January 2021, AS Unit 3, Q3(b)(i) (3 marks): Using the results of the experiment identify the Group 2 metal. [Molar volume of gas at room temperature and pressure = 24.0 dm3 mol−1 ] (3)
- January 2021, AS Unit 3, Q3(b)(ii) (2 marks): The student suggested that the experiment could be made more accurate by increasing the mass of carbonate from 0.33 g to 1.00 g. No changes to the size of the a
- October 2020, AS Unit 2, Q8(a) (1 mark): Which of these compounds could be Q? (1) A barium nitrate B lithium nitrate C magnesium nitrate D rubidium nitrate
- October 2020, AS Unit 2, Q8(b) (1 mark): Which colour and test results are correct for nitrogen dioxide gas? (1) Colour of Colour change of nitrogen dioxide damp litmus paper A brown blue to red B brow
- October 2020, AS Unit 3, Q1(a) (2 marks): Identify, by name or formula, the two gases formed. (2)
- October 2020, AS Unit 3, Q1(b) (1 mark): Identify, by name or formula, the anion present in A. (1)
- October 2020, AS Unit 3, Q1(c) (1 mark): A flame test was carried out on A and a green colour was observed. Identify, by name or formula, the cation present in A. (1)
- October 2020, AS Unit 3, Q1(d) (2 marks): Give the formula of solid A and the formula of the white solid formed on heating. (2) Solid A White solid
- October 2020, AS Unit 3, Q2(b) (6 marks): To identify the cations in sodium chloride and potassium carbonate, a student carried out flame tests using the following method. Step 1 A sample of solid sodi
- January 2020, AS Unit 3, Q1(a)(ii) (2 marks): Name a test, with the expected observation, to confirm the presence of the sodium ion in these compounds. (2) Test Observation
- June 2019, AS Unit 2, Q15(a) (1 mark): What is the white solid, X? (1) A lithium chloride B calcium chloride C strontium bromide D barium bromide
- June 2019, AS Unit 2, Q15(b) (1 mark): What causes the flame colour to be red? (1) A electrons absorb blue and green light as they are promoted B electrons emit red light as they are promoted C blue
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