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Past-paper questions pack

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Questions are numbered; the mark schemes (the answer key) follow on separate pages so the question pages can be handed out alone. www.chemistryaleveltutor.com

OCR AS and A-level Chemistry past-paper questions since 2016 · 34 parts · mark schemes follow the questions · www.chemistryaleveltutor.com · Questions and mark schemes © OCR

1. June 2025 · AS Paper 1 · Q9 · 1 marks ·
9 Which equation describes the second ionisation energy of magnesium? A Mg(g) Mg2+(g) + 2e– B Mg(s) Mg2+(g) + 2e– C Mg+(g) Mg2+(g) + e– D Mg2+(g) + e– Mg+(g) Your answer [1]
2. June 2025 · Paper 1 · Q14 · 1 marks ·
14 Barium is in Group 2 of the periodic table. Which statement(s) about barium is / are correct? 1 Its outer shell electrons are in an s-orbital. 2 It reacts more vigorously with water than magnesium. 3 It has a higher first ionisation energy than magnesium. A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
3. June 2025 · AS Paper 2 · Q2(a)(i) · 1 marks ·
2 This question is about reactions of some Group 2 elements and their compounds. (a) The table below shows the first and second ionisation energies of magnesium and calcium. 1st Ionisation energy 2nd Ionisation energy Group 2 element / kJ mol–1 / kJ mol–1 Mg 738 1451 Ca 590 1145 (i) Write an equation to represent the second ionisation energy of calcium. Include state symbols. ..................................................................................................................................................... [1]
4. June 2025 · AS Paper 2 · Q2(a)(ii) · 6 marks ·
(ii)* Magnesium and calcium differ in their reactivity. Give a balanced equation for the reaction of calcium with water and describe what would be observed. Explain why this is a redox reaction. Explain the difference in reactivity of magnesium and calcium. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [6] Extra answer space if required. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..........................................................................................................................................................
5. June 2024 · Paper 1 · Q4 · 1 marks ·
4 Which compounds of magnesium can be used as ‘antacids’? A Chlorides B Hydroxides C Nitrates D Sulfates Your answer [1]
6. June 2024 · AS Paper 1 · Q7 · 1 marks ·
7 Group 2 compounds can be used in agriculture to neutralise acid soils and in medicine to treat indigestion. Which Group 2 compound is not suitable for either use? A Mg(OH)2 B MgSO4 C CaCO3 D CaO Your answer [1]
7. June 2024 · Paper 1 · Q21(a) · 3 marks ·
21 This question is about redox reactions and electrode potentials. (a) The flowchart shows some reactions of barium and its compounds. Barium Reaction 1 Barium oxide Reaction 2 Barium hydroxide Reaction 3 Barium chloride • Write balanced equations for Reaction 1 and Reaction 2. • Identify the type of reaction in Reaction 3. Reaction 1: equation ....................................................................................................................... Reaction 2: equation ....................................................................................................................... Reaction 3: type of reaction ............................................................................................................ [3]
8. June 2024 · AS Paper 2 · Q2(a)(iii) · 2 marks ·
(iii) Mg forms 2+ ions but Cl usually forms 1– ions in their reactions. Explain why. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [2]
9. June 2024 · AS Paper 2 · Q2(a)(iv) · 1 marks ·
(iv) Magnesium reacts with oxygen in the air. Write the equation for this reaction. ..................................................................................................................................................... [1]
10. June 2024 · AS Paper 2 · Q2(b)(ii) · 3 marks ·
(ii) A student plans to add 0.0100 mol of Ca to 120 cm3 of 0.100 mol dm–3 HCl (aq). When the student carries out this reaction, they are surprised that all the calcium reacts, despite being in excess of the HCl (aq). • Show by calculation that calcium is in excess of the HCl (aq). • Suggest a reason for this unexpected result. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [3]
11. June 2023 · Paper 1 · Q16(b) · 4 marks · AO1
(b) The first and second ionisation energies of magnesium, Mg, and strontium, Sr, in Group 2 are given in the table below. First ionisation energy Second ionisation energy Element / kJ mol–1 / kJ mol–1 Mg +738 +1451 Sr +550 +1064 • Explain why the first ionisation energy of Mg is greater than the first ionisation energy of Sr. • Explain why the second ionisation energy of Sr is greater than the first ionisation energy of Sr. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [4]
12. June 2023 · Paper 1 · Q20(b) · 5 marks · AO1, 2
(b) A student reacts strontium metal with water to make a 250.0 cm3 solution of aqueous strontium hydroxide, Sr(OH)2. The solution contains 0.145 g of strontium hydroxide. • Write an equation for the reaction of strontium with water. • Calculate the pH of this 250.0 cm3 solution of strontium hydroxide at 40 °C. You should refer back to Table 20.1 at the start of (a). Give your answer to 2 decimal places. Equation ................................................................................................................................... Calculation pH = .......................................................... [5]
13. June 2023 · AS Paper 2 · Q2(a)(i) · 2 marks · AO1, 2
2 This question is about some elements in Period 3 and compounds they form. (a) A student adds a small piece of calcium to a beaker containing an excess of water. (i) Construct the equation for the reaction and predict one observation that the student would make. Equation ............................................................................................................................. Observation ........................................................................................................................ ........................................................................................................................................... [2]
14. June 2023 · AS Paper 2 · Q2(a)(ii) · 1 marks · AO1
(ii) Suggest one difference that the student would observe in the reaction of barium with water compared to the reaction of calcium with water. ........................................................................................................................................... ...................................................................................................................................... [1]
15. June 2022 · Paper 1 · Q21(a)(i) · 1 marks · AO2
21 This question is about the reactions of Group 2 metals and their compounds. (a) A student adds magnesium to dilute hydrochloric acid in one test tube. The student adds calcium to dilute hydrochloric acid in a second test tube. A redox reaction takes place in each test tube. (i) Suggest two observations from the student’s experiment that would show that calcium is more reactive than magnesium. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ...................................................................................................................................... [1]
16. June 2022 · Paper 1 · Q21(a)(ii) · 2 marks · AO2
(ii) Write half-equations for the reaction of magnesium with hydrochloric acid. Oxidation half-equation: .................................................................................................... Reduction half-equation: ................................................................................................... [2]
17. June 2022 · Paper 1 · Q21(b)(i) · 5 marks · AO2
(b) A sample of barium oxide is added to distilled water at 25 °C. A colourless solution forms containing barium hydroxide, Ba(OH)2. The solution is made up to 250.0 cm3 with distilled water. The pH of this solution is 13.12. (i) Determine the mass of barium oxide that was used. Give your answer to 3 significant figures. mass of barium oxide = ....................................................... g [5]
18. June 2022 · AS Paper 2 · Q2(a)(i) · 1 marks · AO2
2 This question is about some Group 2 elements and their compounds. (a) Strontium and calcium both react with water. (i) Write an equation for the reaction of strontium with water. ...................................................................................................................................... [1]
19. June 2022 · AS Paper 2 · Q2(a)(iii) · 3 marks · AO1
(iii) Explain why calcium reacts more slowly with water than strontium does. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
20. June 2022 · AS Paper 2 · Q2(b)(i) · 1 marks · AO1
(b) A student adds barium oxide, BaO, to water. A reaction takes place forming a colourless solution. (i) Predict the approximate pH of the colourless solution. pH = ................ [1]
21. November 2021 · AS Paper 2 · Q6(c)(ii) · 2 marks · AO3
(ii) The student observes that the rate of reaction for barium is different from the rate of reaction with strontium. On Fig. 6.1 sketch the graph the student would obtain using barium instead of strontium. [2]
22. November 2021 · AS Paper 2 · Q6(c)(iii) · 4 marks · AO1
(iii) Describe and explain the difference in reactivity of barium and strontium with water. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [4]
23. November 2020 · AS Paper 1 · Q4 · 1 marks · AO1
4 Some Group 2 compounds can be used to neutralise acid soils and to treat acid indigestion. Which Group 2 compound would not be suitable for either use? A BaSO4 B CaCO3 C Ca(OH)2 D Mg(OH)2 Your answer [1]
24. November 2020 · Paper 1 · Q14 · 1 marks · AO1
14 Which statement(s) for Group 2 elements is/are correct? 1 The 2nd ionisation energy of magnesium is greater than the 2nd ionisation energy of calcium. 2 A strontium ion, Sr2+, contains a total of 6 electrons in s orbitals. 3 The equation for the reaction of barium with water is: 2Ba + 2H2O 2BaOH + H2. A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
25. November 2020 · AS Paper 1 · Q23(c) · 4 marks · AO2, 3
(c) A student plans to prepare a solution of Ba(OH)2 from barium by two different reaction routes. Outline 2 reaction routes for preparing a solution of Ba(OH)2 from barium in the laboratory. Include relevant equations. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [4]
26. November 2020 · AS Paper 2 · Q3(b)(ii) · 3 marks · AO1, 2
(ii) The reaction of barium with bromine is more vigorous than the reaction of calcium with bromine. Explain why. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
27. June 2019 · Paper 1 · Q9 · 1 marks · AO1
9 Which statement is not correct for Group 2 hydroxides? A Mg(OH)2 can be used to treat indigestion. B Ca(OH)2 is used in agriculture to neutralise alkaline soils. C The anion in Sr(OH)2 contains 10 electrons. D Ba(OH)2 is a product from the reaction of barium and water. Your answer [1]
28. June 2019 · Paper 1 · Q16(c)(i) · 1 marks · AO2
(c) A student adds an excess of calcium oxide to water in a test tube. In a separate test tube, the student adds an excess of strontium oxide to water. (i) Write the equation for the reaction of calcium oxide with water. State symbols are not required. ...................................................................................................................................... [1]
29. June 2019 · Paper 1 · Q16(c)(ii) · 1 marks · AO1
(ii) Suggest the approximate pH of the two solutions formed in the test tubes. pH with calcium oxide ....................................................................................................... pH with strontium oxide ...................................................................................................... [1]
30. June 2019 · AS Paper 2 · Q1(c)(i) · 1 marks · AO2
(c) A student adds a small amount of strontium to water. When the reaction has finished, the student measures the pH of the final solution. (i) Write the equation for the reaction of strontium with water. ...................................................................................................................................... [1]
31. June 2019 · AS Paper 2 · Q1(c)(ii) · 2 marks · AO2
(ii) Describe two observations which would be different if the student had used calcium in place of strontium. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... [2]
32. June 2017 · Paper 1 · Q17(b) · 3 marks ·
(b) The reactivity of the Group 2 elements Mg–Ba increases down the group. Explain why. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3]
33. June 2016 · AS Paper 2 · Q1(a)(ii) · 1 marks · AO1
(ii) Explain what happens when magnesium is oxidised in terms of electron transfer. ........................................................................................................................................... ...................................................................................................................................... [1]
34. June 2016 · AS Paper 2 · Q1(b)(i) · 1 marks · AO2
(b) The trend in the first and second ionisation energies of Group 2 elements can be linked to the increase in chemical reactivity down the group. The first and second ionisation energies of calcium and strontium are given in the table. First ionisation energy Second ionisation energy Element / kJ mol–1 / kJ mol–1 Ca 590 1145 Sr 550 1064 (i) Write an equation, including state symbols, to represent the second ionisation energy of strontium. ...................................................................................................................................... [1]

Mark schemes

1. June 2025 · AS Paper 1 · Q9
Mark scheme June 2025 Paper 1 Q9
2. June 2025 · Paper 1 · Q14
Mark scheme June 2025 Paper 1 Q14
3. June 2025 · AS Paper 2 · Q2(a)(i)
Mark scheme June 2025 Paper 2 Q2(a)(i)
4. June 2025 · AS Paper 2 · Q2(a)(ii)
Mark scheme June 2025 Paper 2 Q2(a)(ii)
5. June 2024 · Paper 1 · Q4
Mark scheme June 2024 Paper 1 Q4
6. June 2024 · AS Paper 1 · Q7
Mark scheme June 2024 Paper 1 Q7
7. June 2024 · Paper 1 · Q21(a)
Mark scheme June 2024 Paper 1 Q21(a)
8. June 2024 · AS Paper 2 · Q2(a)(iii)
Mark scheme June 2024 Paper 2 Q2(a)(iii)
9. June 2024 · AS Paper 2 · Q2(a)(iv)
Mark scheme June 2024 Paper 2 Q2(a)(iv)
10. June 2024 · AS Paper 2 · Q2(b)(ii)
Mark scheme June 2024 Paper 2 Q2(b)(ii)
11. June 2023 · Paper 1 · Q16(b)
Mark scheme June 2023 Paper 1 Q16(b)
12. June 2023 · Paper 1 · Q20(b)
Mark scheme June 2023 Paper 1 Q20(b)
13. June 2023 · AS Paper 2 · Q2(a)(i)
Mark scheme June 2023 Paper 2 Q2(a)(i)
14. June 2023 · AS Paper 2 · Q2(a)(ii)
Mark scheme June 2023 Paper 2 Q2(a)(ii)
15. June 2022 · Paper 1 · Q21(a)(i)
Mark scheme June 2022 Paper 1 Q21(a)(i)
16. June 2022 · Paper 1 · Q21(a)(ii)
Mark scheme June 2022 Paper 1 Q21(a)(ii)
17. June 2022 · Paper 1 · Q21(b)(i)
Mark scheme June 2022 Paper 1 Q21(b)(i)
18. June 2022 · AS Paper 2 · Q2(a)(i)
Mark scheme June 2022 Paper 2 Q2(a)(i)
19. June 2022 · AS Paper 2 · Q2(a)(iii)
Mark scheme June 2022 Paper 2 Q2(a)(iii)
20. June 2022 · AS Paper 2 · Q2(b)(i)
Mark scheme June 2022 Paper 2 Q2(b)(i)
21. November 2021 · AS Paper 2 · Q6(c)(ii)
Mark scheme November 2021 Paper 2 Q6(c)(ii)
22. November 2021 · AS Paper 2 · Q6(c)(iii)
Mark scheme November 2021 Paper 2 Q6(c)(iii)
23. November 2020 · AS Paper 1 · Q4
Mark scheme November 2020 Paper 1 Q4
24. November 2020 · Paper 1 · Q14
Mark scheme November 2020 Paper 1 Q14
25. November 2020 · AS Paper 1 · Q23(c)
Mark scheme November 2020 Paper 1 Q23(c)
26. November 2020 · AS Paper 2 · Q3(b)(ii)
Mark scheme November 2020 Paper 2 Q3(b)(ii)
27. June 2019 · Paper 1 · Q9
Mark scheme June 2019 Paper 1 Q9
28. June 2019 · Paper 1 · Q16(c)(i)
Mark scheme June 2019 Paper 1 Q16(c)(i)
29. June 2019 · Paper 1 · Q16(c)(ii)
Mark scheme June 2019 Paper 1 Q16(c)(ii)
30. June 2019 · AS Paper 2 · Q1(c)(i)
Mark scheme June 2019 Paper 2 Q1(c)(i)
31. June 2019 · AS Paper 2 · Q1(c)(ii)
Mark scheme June 2019 Paper 2 Q1(c)(ii)
32. June 2017 · Paper 1 · Q17(b)
Mark scheme June 2017 Paper 1 Q17(b)
33. June 2016 · AS Paper 2 · Q1(a)(ii)
Mark scheme June 2016 Paper 2 Q1(a)(ii)
34. June 2016 · AS Paper 2 · Q1(b)(i)
Mark scheme June 2016 Paper 2 Q1(b)(i)