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Lattice enthalpy and Born–Haber cycles

Past-paper questions pack

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OCR AS and A-level Chemistry past-paper questions since 2016 · 27 parts · mark schemes follow the questions · www.chemistryaleveltutor.com · Questions and mark schemes © OCR

1. June 2025 · Paper 1 · Q3 · 1 marks ·
3 The diagram shows the Born-Haber cycle for sodium oxide, Na2O. 2Na+(g) + O2–(g) 2Na+(g) + O(g) + 2e– 2Na+(g) + O–(g) + e– 2Na(g) + O(g) 2Na(g) + ½O2(g) 2Na(s) + ½O2(g) Na2O(s) Why is the value for the second electron affinity of oxygen positive? A An electron is added to a high energy orbital. B An electron is added to a negative ion. C An electron is removed from a gaseous atom. D An electron is removed from a positive ion. Your answer [1]
2. June 2024 · Paper 1 · Q16(c)(i) · 2 marks ·
(c) Manganese(II) oxide, MnO, has a giant ionic lattice structure. The table shows the enthalpy changes that are needed to determine the lattice enthalpy of MnO. enthalpy change / kJ mol–1 atomisation of manganese +281 atomisation of oxygen +249 first ionisation energy of manganese +717 second ionisation energy of manganese +1509 first electron affinity of oxygen –141 second electron affinity of oxygen +798 formation of manganese(II) oxide −385 (i) Define the term lattice enthalpy. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [2]
3. June 2024 · Paper 1 · Q16(c)(ii) · 3 marks ·
(ii) The diagram shows an incomplete Born-Haber cycle that can be used to determine the lattice enthalpy of MnO. Mn2+(g) + O(g) + 2e– Mn2+(g) + O2–(g) Mn2+(g) + O2(g) + 2e– 1 2 ............................... Mn+(g) + O2(g) + e– 1 2 ............................... Mn(s) + O2(g) 1 2 ............................... Complete the diagram by adding the species present on the dotted lines, include state symbols. [3]
4. June 2024 · Paper 1 · Q16(c)(iii) · 2 marks ·
(iii) Calculate the lattice enthalpy of MnO. lattice enthalpy = ............................................ kJ mol–1 [2]
5. June 2023 · Paper 1 · Q8 · 1 marks · AO1
8 Which compound requires the most energy to convert one mole into its gaseous ions? A NaF B Na2O C MgF2 D MgO Your answer [1]
6. June 2023 · Paper 1 · Q16(a)(i) · 4 marks · AO1
16 This question is about energy changes. (a) Lattice enthalpies can be determined indirectly using Born-Haber cycles. The table below shows the energy changes that are needed to determine the lattice enthalpy of barium iodide, BaI2. Energy term Energy change / kJ mol–1 formation of barium iodide –602 1st electron affinity of iodine –296 1st ionisation energy of barium +503 2nd ionisation energy of barium +965 atomisation of iodine +107 atomisation of barium +180 (i) The diagram below shows an incomplete Born-Haber cycle that can be used to calculate the lattice enthalpy of barium iodide. On the dotted lines, add the species present, including state symbols. Ba2+(g) + 2I(g) + 2e– ............................ ............................ ............................ Ba(s) + 2I(g) ............................ BaI2(s) [4]
7. June 2023 · Paper 1 · Q16(a)(ii) · 2 marks · AO2
(ii) Calculate the lattice enthalpy of barium iodide. lattice enthalpy = ............................................ kJ mol–1 [2]
8. June 2023 · Paper 3 · Q2(a)(ii) · 3 marks · AO2
(ii) A student carries out an experiment to determine the enthalpy change of solution of RbCl O3 using the method below. • A 2.00 g sample of solid RbCl O3 is added to water in a well-insulated container. The initial temperature is 23.0 °C. • The mixture is stirred until all the RbCl O3 has dissolved. The final temperature is 21.5 °C. The final solution has a mass of 102 g. Determine the enthalpy change of solution, ΔsolH, of RbCl O3 in kJ mol–1. Assume that the specific heat capacity of the solution is the same as that of pure water. ΔsolH (RbCl O3) = ........................................... kJ mol–1 [3]
9. June 2022 · Paper 1 · Q9 · 1 marks · AO1
9 Which equation represents the change that accompanies the standard enthalpy change of atomisation of bromine? A ½ Br2(l) Br(g) B Br2(l) 2Br(g) C ½ Br2(g) Br(g) D Br2(g) 2Br(g) Your answer [1]
10. June 2022 · Paper 3 · Q5(a) · 6 marks · AO3
5 This question is about energy changes. (a)* A student plans to determine the enthalpy change of hydration of calcium ions. The student finds the information below from data tables. Enthalpy change ∆H / kJ mol–1 Lattice enthalpy of calcium chloride –2223 Enthalpy change of hydration of chloride ions –378 The student carries out an experiment to find the enthalpy change of solution of calcium chloride. Student’s method: • Weigh a bottle containing calcium chloride and weigh a polystyrene cup. • Add water from a measuring cylinder to the polystyrene cup and measure its temperature. • Add the calcium chloride, stir the mixture, and measure the maximum temperature of the final solution. • Weigh the empty bottle and weigh the polystyrene cup with the final solution. Mass readings Mass of bottle + calcium chloride / g 27.45 Mass of empty bottle / g 18.17 Mass of polystyrene cup / g 21.24 Mass of polystyrene cup + final solution / g 127.84 Temperature readings Initial temperature of water / °C 21.0 Maximum temperature of final solution / °C 39.5 Calculate the enthalpy change of solution of calcium chloride and determine the enthalpy change of hydration of calcium ions. Show your working, including an energy cycle linking the energy changes. Assume that the density and specific heat capacity, c, of the solution are the same as for water. [6] ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................
11. November 2021 · Paper 1 · Q16(c)(i) · 1 marks · AO1
(c) The enthalpy change of solution for magnesium fluoride, MgF2, can be determined indirectly using an energy cycle based on the enthalpy changes below. Enthalpy change Energy / kJ mol–1 Lattice enthalpy of magnesium fluoride –2926 Hydration of magnesium ions –1920 Hydration of fluoride ions –506 (i) Explain what is meant by enthalpy change of solution. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
12. November 2021 · Paper 1 · Q16(c)(ii) · 2 marks · AO2
(ii) On the dotted lines, add the species present, including state symbols. Mg2+(g) + 2F–(g) .................................................... MgF2(s) .................................................... [2]
13. November 2021 · Paper 1 · Q16(c)(iii) · 1 marks · AO2
(iii) Calculate the enthalpy change of solution of MgF2. enthalpy change of solution = ............................................ kJ mol–1 [1]
14. November 2021 · Paper 1 · Q16(c)(iv) · 4 marks · AO1, 3
(iv) The enthalpy changes of solution of the magnesium halides show a trend from MgF2 to MgI2. Explain why it is difficult to predict whether the enthalpy change of solution becomes more exothermic or less exothermic down the group from MgF2 to MgI2. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [4]
15. November 2020 · Paper 1 · Q16(d)(i) · 2 marks · AO1
(d) The enthalpy change of hydration of bromide ions can be determined using the enthalpy changes in Table 16.2. Enthalpy change Energy / kJ mol−1 1st ionisation energy of magnesium +736 2nd ionisation energy of magnesium +1450 atomisation of bromine +112 atomisation of magnesium +148 electron affinity of bromine −325 formation of magnesium bromide −525 hydration of bromide ion to be calculated hydration of magnesium ion −1926 solution of magnesium bromide −186 Table 16.2 (i) An incomplete energy cycle based on Table 16.2 is shown below. On the dotted lines, add the species present, including state symbols. ............................................ Mg2+(g) + 2Br–(g) Mg+(g) + 2Br(g) + e– Mg(g) + 2Br(g) Mg(s) + 2Br(g) ............................................ Mg2+(aq) + 2Br–(g) MgBr2(s) Mg2+(aq) + 2Br–(aq) [2]
16. November 2020 · Paper 1 · Q16(d)(ii) · 2 marks · AO2
(ii) Using your completed energy cycle in 16(d)(i), calculate the enthalpy change of hydration of bromide ions. enthalpy change of hydration = ........................................... kJ mol−1 [2]
17. November 2020 · Paper 1 · Q16(d)(iii) · 3 marks · AO1, 2
(iii) Write the equation for the lattice enthalpy of magnesium bromide and calculate the lattice enthalpy of magnesium bromide. Equation ............................................................................................................................ Calculation lattice enthalpy = ............................................ kJ mol−1 [3]
18. June 2019 · Paper 1 · Q16(d)(i) · 4 marks · AO1
(d) The table below shows enthalpy changes involving potassium, oxygen and potassium oxide, K2O. Enthalpy change / kJ mol−1 formation of potassium oxide –363 1st electron affinity of oxygen –141 2nd electron affinity of oxygen +790 1st ionisation energy of potassium +419 atomisation of oxygen +249 atomisation of potassium +89 (i) The incomplete Born–Haber cycle below can be used to determine the lattice enthalpy of potassium oxide. In the boxes, complete the species present in the cycle. Include state symbols for the species. 2K+(g) + O(g) + 2e– 2K(s) + O(g) K2O(s) [4]
19. June 2019 · Paper 1 · Q16(d)(ii) · 2 marks · AO2
(ii) Calculate the lattice enthalpy of potassium oxide. lattice enthalpy = ............................................ kJ mol−1 [2]
20. June 2019 · Paper 1 · Q16(e)(ii) · 2 marks · AO1
(ii) The lattice enthalpy of sodium oxide is more exothermic than that of potassium oxide. Explain why. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
21. June 2019 · Paper 3 · Q5(a)(i) · 6 marks · AO3
5 This question is about copper(II) sulfate, CuSO4, and sodium thiosulfate, Na2S2O3. (a) The enthalpy change of reaction, ∆rH, for converting anhydrous copper(II) sulfate to hydrated copper(II) sulfate is difficult to measure directly by experiment. CuSO4(s) + 5H2O(l) → CuSO4•5H2O(s) ∆rH reaction 5.1 The enthalpy changes of solution of anhydrous and hydrated copper(II) sulfate can be measured by experiment. The reactions are shown below. In the equations, ‘aq’ represents an excess of water. CuSO4(s) + aq → Cu2+(aq) + SO4 2−(aq) ∆solH(CuSO4(s)) reaction 5.2 CuSO4•5H2O(s) + aq → Cu2+(aq) + SO4 2−(aq) ∆solH(CuSO4•5H2O(s)) reaction 5.3 Experiment 1 A student carries out an experiment to find ∆solH(CuSO4(s)) for reaction 5.2. Student’s method • Weigh a bottle containing CuSO4(s) and weigh a polystyrene cup. • Add about 50 cm3 of water to the polystyrene cup and measure its temperature. • Add the CuSO4(s), stir the mixture, and measure the final temperature. • Weigh the empty bottle and weigh the polystyrene cup with final solution. Mass readings Mass of bottle + CuSO4(s) / g 28.04 Mass of empty bottle / g 20.06 Mass of polystyrene cup / g 23.43 Mass of polystyrene cup + final solution / g 74.13 Temperature readings Initial temperature of water / °C 20.5 Temperature of final solution / °C 34.0 Experiment 2 The student carries out a second experiment with CuSO4•5H2O (reaction 5.3). The student uses the same method as in Experiment 1. The student calculates ∆solH(CuSO4•5H2O(s)) as +8.43 kJ mol−1. (i)* Calculate ∆solH(CuSO4(s)) for reaction 5.2 and determine the enthalpy change of reaction 5.1, ∆rH. Assume that the specific heat capacity, c, of the solution is the same as for water. Show your working, including an energy cycle linking the enthalpy changes. [6] ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... Additional answer space if required ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................
22. June 2018 · Paper 1 · Q13 · 1 marks · AO1
13 Which enthalpy change(s) is/are endothermic? 1 The bond enthalpy of the C–H bond 2 The second electron affinity of oxygen 3 The standard enthalpy change of formation of magnesium A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
23. June 2018 · Paper 1 · Q16(a)(i) · 2 marks ·
SECTION B Answer all the questions. 16 This question is about enthalpy changes. (a) Table 16.1 shows enthalpy changes that can be used to determine the enthalpy change of hydration of fluoride ions, F–. Enthalpy change Energy / kJ mol–1 Hydration of Ca2+ –1609 Solution of CaF2 +13 Lattice enthalpy of CaF2 –2630 Table 16.1 (i) Explain what is meant by the term enthalpy change of hydration. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
24. June 2018 · Paper 1 · Q16(a)(ii) · 4 marks ·
(ii) The enthalpy change of hydration of F– can be determined using the enthalpy changes in Table 16.1 and the incomplete energy cycle below. On the dotted lines, add the species present, including state symbols. ....................................................... ....................................................... lattice enthalpy ....................................................... ....................................................... [4]
25. June 2018 · Paper 1 · Q16(a)(iii) · 2 marks ·
(iii) Calculate the enthalpy change of hydration of fluoride ions, F–. enthalpy change of hydration = ............................................ kJ mol–1 [2]
26. June 2018 · Paper 1 · Q16(a)(iv) · 2 marks ·
(iv) Predict how the enthalpy changes of hydration of F– and Cl – would differ. Explain your answer. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
27. June 2017 · Paper 1 · Q17(d)(ii) · 2 marks ·
(ii) The change that accompanies the standard enthalpy change of atomisation of iodine. Equation with state symbols ........................................................................................................................................... Explanation of entropy change .......................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]

Mark schemes

1. June 2025 · Paper 1 · Q3
Mark scheme June 2025 Paper 1 Q3
2. June 2024 · Paper 1 · Q16(c)(i)
Mark scheme June 2024 Paper 1 Q16(c)(i)
3. June 2024 · Paper 1 · Q16(c)(ii)
Mark scheme June 2024 Paper 1 Q16(c)(ii)
4. June 2024 · Paper 1 · Q16(c)(iii)
Mark scheme June 2024 Paper 1 Q16(c)(iii)
5. June 2023 · Paper 1 · Q8
Mark scheme June 2023 Paper 1 Q8
6. June 2023 · Paper 1 · Q16(a)(i)
Mark scheme June 2023 Paper 1 Q16(a)(i)
7. June 2023 · Paper 1 · Q16(a)(ii)
Mark scheme June 2023 Paper 1 Q16(a)(ii)
8. June 2023 · Paper 3 · Q2(a)(ii)
Mark scheme June 2023 Paper 3 Q2(a)(ii)
9. June 2022 · Paper 1 · Q9
Mark scheme June 2022 Paper 1 Q9
10. June 2022 · Paper 3 · Q5(a)
Mark scheme June 2022 Paper 3 Q5(a)
11. November 2021 · Paper 1 · Q16(c)(i)
Mark scheme November 2021 Paper 1 Q16(c)(i)
12. November 2021 · Paper 1 · Q16(c)(ii)
Mark scheme November 2021 Paper 1 Q16(c)(ii)
13. November 2021 · Paper 1 · Q16(c)(iii)
Mark scheme November 2021 Paper 1 Q16(c)(iii)
14. November 2021 · Paper 1 · Q16(c)(iv)
Mark scheme November 2021 Paper 1 Q16(c)(iv)
15. November 2020 · Paper 1 · Q16(d)(i)
Mark scheme November 2020 Paper 1 Q16(d)(i)
16. November 2020 · Paper 1 · Q16(d)(ii)
Mark scheme November 2020 Paper 1 Q16(d)(ii)
17. November 2020 · Paper 1 · Q16(d)(iii)
Mark scheme November 2020 Paper 1 Q16(d)(iii)
18. June 2019 · Paper 1 · Q16(d)(i)
Mark scheme June 2019 Paper 1 Q16(d)(i)
19. June 2019 · Paper 1 · Q16(d)(ii)
Mark scheme June 2019 Paper 1 Q16(d)(ii)
20. June 2019 · Paper 1 · Q16(e)(ii)
Mark scheme June 2019 Paper 1 Q16(e)(ii)
21. June 2019 · Paper 3 · Q5(a)(i)
Mark scheme June 2019 Paper 3 Q5(a)(i)
22. June 2018 · Paper 1 · Q13
Mark scheme June 2018 Paper 1 Q13
23. June 2018 · Paper 1 · Q16(a)(i)
Mark scheme June 2018 Paper 1 Q16(a)(i)
24. June 2018 · Paper 1 · Q16(a)(ii)
Mark scheme June 2018 Paper 1 Q16(a)(ii)
25. June 2018 · Paper 1 · Q16(a)(iii)
Mark scheme June 2018 Paper 1 Q16(a)(iii)
26. June 2018 · Paper 1 · Q16(a)(iv)
Mark scheme June 2018 Paper 1 Q16(a)(iv)
27. June 2017 · Paper 1 · Q17(d)(ii)
Mark scheme June 2017 Paper 1 Q17(d)(ii)