Born–Haber cycles: AQA A‑Level Chemistry questions

AQA A-Level Chemistry past-paper questions on 3.1.8.1 Born–Haber cycles, 2008–2025, with mark schemes and examiner’s reports where available.

All 105 questions on Born–Haber cycles, as a list

June 2025, Paper 3, Q01.1 (1 mark): Give the equation, including state symbols, for the process that occurs when the enthalpy of solution of potassium hydroxide is determined. [1 mark]
June 2025, Paper 3, Q01.3 (2 marks): Table 2 shows some enthalpy change data. Table 2 Enthalpy change / kJ mol–1 Enthalpy of lattice formation of potassium hydroxide –789 Enthalpy of hydration of p
June 2024, Paper 1, Q08.1 (1 mark): Theoretical values for enthalpies of lattice dissociation can be calculated using a perfect ionic model. State the meaning of the term perfect ionic model. [1 m
June 2024, Paper 1, Q08.2 (2 marks): Enthalpies of lattice dissociation can also be obtained from Born–Haber cycles. Figure 3 shows an incomplete Born–Haber cycle for the formation of sodium oxide.
June 2024, Paper 1, Q08.3 (2 marks): Table 4 shows some enthalpy changes. Table 4 Enthalpy change ΔH / kJ mol–1 Enthalpy of atomisation of oxygen +248 Enthalpy of atomisation of sodium +109 Enthalp
June 2024, Paper 1, Q08.4 (1 mark): Explain why the second electron affinity of oxygen has a positive value. [1 mark]
June 2024, Paper 1, Q08.5 (2 marks): Explain why the enthalpy of lattice dissociation for sodium oxide is greater than the enthalpy of lattice dissociation for sodium chloride. [2 marks]
June 2024, Paper 1, Q08.6 (2 marks): Sodium chloride dissolves in water. Table 5 shows some more enthalpy changes. Table 5 Enthalpy change ΔH / kJ mol–1 Enthalpy of hydration for Cl– ions –364 Enth
June 2024, Paper 1, Q08.7 (1 mark): Give a reason why data books do not contain a value for the enthalpy of solution of sodium oxide. [1 mark]
June 2023, Paper 1, Q05.1 (2 marks): Table 2 shows some enthalpy change data. Table 2 Enthalpy change / kJ mol–1 Ca2+(g) → Ca2+(aq) –1650 Cl–(g) → Cl–(aq) –364 Ca2+(g) + 2 Cl– (g) → CaCl2(s) –2237
June 2023, Paper 1, Q05.2 (1 mark): Use your answer to Question 05.1 to deduce how the temperature changes when calcium chloride dissolves in water. [1 mark]
June 2023, Paper 1, Q05.3 (2 marks): Explain why the enthalpy of hydration of fluoride ions is more negative than the enthalpy of hydration of chloride ions. [2 marks]
June 2023, Paper 1, Q05.4 (2 marks): Figure 2 shows an incomplete Born–Haber cycle for calcium chloride. Figure 2 Complete the Born–Haber cycle by writing the formulas of the missing species on eac
June 2023, Paper 1, Q05.5 (2 marks): Table 3 shows some enthalpy change data. Table 3 Enthalpy change / kJ mol–1 Enthalpy of atomisation of calcium +193 First ionisation energy of calcium +590 Enth
June 2023, Paper 1, Q05.7 (6 marks): Table 4 shows lattice enthalpies based on a perfect ionic model and lattice enthalpies from Born–Haber cycles for three metal chlorides. Table 4 Lattice enthalp
June 2022, Paper 3, Q01.1 (2 marks): Define the term enthalpy of lattice dissociation. [2 marks]
June 2022, Paper 3, Q01.2 (3 marks): The enthalpy of solution for ammonium nitrate is the enthalpy change for the reaction shown. NH4NO3(s) + aq → NH4+(aq) + NO3−(aq) ∆H = +26 kJ mol−1 Table 1 NH4+
November 2021, Paper 1, Q01.2 (3 marks): Complete Figure 1 by writing the formulas, including state symbols, of the appropriate species on each of the three blank lines. [3 marks]
November 2021, Paper 1, Q01.3 (2 marks): Table 1 shows some enthalpy data. Table 1 Enthalpy change / kJ mol–1 Enthalpy of formation of calcium chloride –795 Enthalpy of atomisation of calcium +193 Firs
November 2021, Paper 1, Q01.4 (1 mark): Magnesium chloride dissolves in water. Give an equation, including state symbols, to represent the process that occurs when the enthalpy of solution of magnesiu
November 2021, Paper 1, Q01.5 (2 marks): Table 2 shows some enthalpy data. Table 2 Enthalpy change / kJ mol–1 Enthalpy of lattice dissociation of MgCl2 +2493 Enthalpy of hydration of Mg2+(g) –1920 Enth
November 2021, Paper 1, Q01.6 (2 marks): The enthalpy of hydration of Ca2+(g) is –1650 kJ mol–1 Suggest why this value is less exothermic than that of Mg2+(g) [2 marks]
November 2020, Paper 1, Q01.1 (3 marks): Figure 1 shows a Born–Haber cycle for the formation of strontium chloride, SrCl2 Figure 1 Table 1 shows some thermodynamic data. Table 1 Enthalpy change / kJ mo
November 2020, Paper 1, Q01.2 (1 mark): Draw a line from each substance to the enthalpy of lattice formation of that substance. [1 mark] Substance Enthalpy of lattice formation / kJ mol–1 MgCl2 –2018
November 2020, Paper 1, Q01.3 (1 mark): State why there is a difference between the theoretical and experimental values. [1 mark]
November 2020, Paper 1, Q01.4 (2 marks): Table 3 shows enthalpy of hydration values for ions of some Group 1 elements. Table 3 Li+(g) Na+(g) K+(g) Enthalpy of hydration / kJ mol–1 –519 –406 –322 Explai
November 2020, Paper 1, Q01.5 (3 marks): Calcium bromide dissolves in water. Table 4 shows some enthalpy data. Table 4 Enthalpy change / kJ mol–1 Enthalpy of solution of calcium bromide –110 Enthalpy o
June 2019, Paper 1, Q01.1 (2 marks): Complete Figure 1 by writing the formulas, including state symbols, of the appropriate species on each of the two blank lines. [2 marks]
June 2019, Paper 1, Q01.2 (2 marks): Use Figure 1 and the data in Table 1 to calculate the standard enthalpy of atomisation of iodine. [2 marks] Standard enthalpy of atomisation of iodine kJ mol-1
June 2019, Paper 1, Q01.3 (1 mark): The enthalpy of lattice formation for caesium iodide in Table 1 is a value obtained by experiment. The value obtained by calculation using the perfect ionic mod
June 2019, Paper 1, Q01.4 (4 marks): Use data from Table 2 to show that this reaction is not feasible at 298 K CsI(s) → Cs(s) + 1 2 I2(s) ∆Ho = +337 kJ mol–1 Table 2 CsI(s) Cs(s) I2(s) So / J K–1 m
June 2018, Paper 1, Q01.1 (3 marks): Figure 1 shows a Born–Haber cycle for the formation of magnesium oxide. Complete Figure 1 by writing the missing symbols on the appropriate energy levels. [3 ma
June 2018, Paper 1, Q01.2 (3 marks): Table 1 contains some thermodynamic data. Table 1 Enthalpy change / kJ mol–1 Enthalpy of formation for magnesium oxide –602 Enthalpy of atomisation for magnesiu
June 2018, Paper 3, Q14 (1 mark): Which equation represents the process that occurs when the standard enthalpy of atomisation of iodine is measured? [1 mark] A I2(s)  I(g) B I2(s)  2I(g) C I2(
June 2018, Paper 3, Q33 (1 mark): Lattice enthalpy values can be obtained from Born–Haber cycles and by calculations based on a perfect ionic model. Which compound shows the greatest percentage
June 2017, Paper 1, Q01.1 (2 marks): Define the term enthalpy of lattice formation. [2 marks
June 2017, Paper 1, Q01.2 (2 marks): Some enthalpy change data are shown in Table 1. Table 1 Enthalpy change / kJ mol−1 AgI(s) → Ag+(aq) + I–(aq) +112 Ag+(g) → Ag+(aq) −464 I–(g) → I–(aq) −293 Use
June 2017, Paper 1, Q01.3 (2 marks): A calculation of the enthalpy of lattice formation of silver iodide based on a perfect ionic model gives a smaller numerical value than the value calculated in
Specimen, Paper 1, Q09.3 (2 marks): Lattice enthalpy of dissociation = kJ mol –1
Specimen, Paper 1, Q09.4 (2 marks): 6
June 2016, CHEM5 (old spec), Q2(a)(i) (3 marks): Complete Figure 1 by writing the formulae, including state symbols, of the appropriate species on each of the three blank lines. [3 marks] Figure 1 2K+(g) + 2e–
June 2016, CHEM5 (old spec), Q2(a)(ii) (3 marks): Table 1 shows some enthalpy data. Table 1 Use the data in Table 1 to calculate the enthalpy of lattice dissociation of potassium oxide, K2O [3 marks] Enthalpy c
June 2016, CHEM5 (old spec), Q2(b) (2 marks): Explain why the enthalpy of lattice dissociation of potassium oxide is less endothermic than that of sodium oxide. [2 marks]
June 2016, CHEM5 (old spec), Q3(a) (1 mark): Write the equation, including state symbols, for the process corresponding to the enthalpy of solution of magnesium chloride. [1 mark]
June 2016, CHEM5 (old spec), Q3(b) (2 marks): Use these data to calculate the standard enthalpy of solution of magnesium chloride. Enthalpy of lattice dissociation of MgCl2 = +2493 kJ mol–1 Enthalpy of hydr
June 2016, CHEM5 (old spec), Q3(c) (3 marks): Solubility is the measure of how much of a substance can be dissolved in water to make a saturated solution. A salt solution is saturated when an undissolved so
June 2015, CHEM5 (old spec), Q1(a) (2 marks): Define the term electron affinity for chlorine. [2 marks]
June 2015, CHEM5 (old spec), Q1(b) (6 marks): Complete this Born–Haber cycle for magnesium chloride by giving the missing species on the dotted lines. Include state symbols where appropriate. The energy lev
June 2015, CHEM5 (old spec), Q1(c) (3 marks): Table 1 contains some enthalpy data. Table 1 Use your Born–Haber cycle from Question 1 (b) and data from Table 1 to calculate a value for the electron affinity
June 2015, CHEM5 (old spec), Q1(d)(i) (2 marks): Explain why there is a difference between the hydration enthalpies of the magnesium and sodium ions. [2 marks]
June 2015, CHEM5 (old spec), Q1(d)(ii) (2 marks): Use data from Table 1 and Table 2 to calculate a value for the enthalpy change when one mole of magnesium chloride dissolves in water. [2 marks]
June 2014, CHEM5 (old spec), Q1(a) (1 mark): Write an equation for the process that has an enthalpy change equal to the electron affinity of chlorine. [1 mark]
June 2014, CHEM5 (old spec), Q1(b) (2 marks): In terms of electrostatic forces, suggest why the electron affinity of fluorine has a negative value. [2 marks]
June 2014, CHEM5 (old spec), Q1(c)(i) (3 marks): Complete the Born–Haber cycle for silver fluoride by adding the missing species on the dotted lines. [3 marks] Ag+(g) + Ag+(g) + F –(g) AgF(s) Ag+(g) + Ag(g) +
June 2014, CHEM5 (old spec), Q1(c)(ii) (2 marks): Use the cycle in Question 1 (c) (i) and the data in Table 1 to calculate a value, in kJ mol–1, for the bond enthalpy of the fluorine–fluorine bond. [2 marks] Ta
June 2014, CHEM5 (old spec), Q1(d)(i) (2 marks): Explain why the theoretical enthalpy of lattice dissociation for silver fluoride is different from the experimental value that can be calculated using a Born–Ha
June 2014, CHEM5 (old spec), Q1(d)(ii) (2 marks): The theoretical enthalpy of lattice dissociation for silver chloride is +770 kJ mol–1. Explain why this value is less than the value for silver fluoride. [2 mar
June 2014, CHEM5 (old spec), Q2(a) (2 marks): Define the term enthalpy of hydration of an ion. [2 marks]
June 2014, CHEM5 (old spec), Q2(b) (2 marks): Use data from Table 2 to calculate a value for the enthalpy of hydration of the chloride ion. [2 marks]
June 2014, CHEM5 (old spec), Q2(c) (2 marks): Suggest why hydration of the chloride ion is an exothermic process. [2 marks]
June 2013, CHEM5 (old spec), Q1(a) (2 marks): Define the term lattice enthalpy of dissociation.
June 2013, CHEM5 (old spec), Q1(b) (1 mark): Lattice enthalpy can be calculated theoretically using a perfect ionic model. Explain the meaning of the term perfect ionic model. (1 mark)
June 2013, CHEM5 (old spec), Q1(c) (2 marks): Suggest two properties of ions that influence the value of a lattice enthalpy calculated using a perfect ionic model. Property 1 Property 2
June 2013, CHEM5 (old spec), Q1(d) (3 marks): Use the data in the table to calculate a value for the lattice enthalpy of dissociation for silver chloride.
June 2013, CHEM5 (old spec), Q1(e) (2 marks): Predict whether the magnitude of the lattice enthalpy of dissociation that you have calculated in part (d) will be less than, equal to or greater than the value
June 2013, CHEM5 (old spec), Q2(a) (3 marks): By describing the nature of the attractive forces involved, explain why the value for the enthalpy of hydration for the chloride ion is more negative than that
June 2013, CHEM5 (old spec), Q2(b) (2 marks): The enthalpy of hydration for the potassium ion is –322 kJ mol–1. The lattice enthalpy of dissociation for potassium bromide is +670 kJ mol–1. Calculate the ent
January 2013, CHEM5 (old spec), Q1(b) (1 mark): Explain why the enthalpy of atomisation of chlorine is exactly half the bond dissociation enthalpy of chlorine. (1 mark) 1
January 2013, CHEM5 (old spec), Q2(a) (1 mark): Write an equation, including state symbols, for the reaction that has an enthalpy change equal to the lattice dissociation enthalpy of magnesium chloride. (1 ma
January 2013, CHEM5 (old spec), Q2(b) (2 marks): Explain why the lattice dissociation enthalpy of magnesium chloride is greater than that of calcium chloride.
January 2013, CHEM5 (old spec), Q2(c) (2 marks): Explain why the lattice dissociation enthalpy of magnesium oxide is greater than that of magnesium chloride.
January 2013, CHEM5 (old spec), Q2(d) (3 marks): When magnesium chloride dissolves in water, the enthalpy of solution is –155 kJ mol–1. The enthalpy of hydration of chloride ions is –364 kJ mol–1. Calculate th
January 2013, CHEM5 (old spec), Q2(e) (2 marks): Energy is released when a magnesium ion is hydrated because magnesium ions attract water molecules. Explain why magnesium ions attract water molecules. You may
January 2013, CHEM5 (old spec), Q2(f) (1 mark): Suggest why a value for the enthalpy of solution of magnesium oxide is not found in any data books. (1 mark)
June 2012, CHEM5 (old spec), Q3(a) (2 marks): Explain the meaning of the term electron affinity.
June 2012, CHEM5 (old spec), Q3(c) (2 marks): Explain why the hydration enthalpy of the fluoride ion is more negative than the hydration enthalpy of the chloride ion.
June 2012, CHEM5 (old spec), Q3(d)(i) (3 marks): Use these data and data from the table to calculate a value for the lattice enthalpy of dissociation of silver fluoride.
January 2012, CHEM5 (old spec), Q1(a) (3 marks): Define the term enthalpy of lattice dissociation.
January 2012, CHEM5 (old spec), Q1(b) (1 mark): In terms of the forces acting on particles, suggest one reason why the first electron affinity of oxygen is an exothermic process. (1 mark)
January 2012, CHEM5 (old spec), Q1(c) (4 marks): Complete the Born–Haber cycle for magnesium oxide by drawing the missing energy levels, symbols and arrows. The standard enthalpy change values are given in kJ
January 2012, CHEM5 (old spec), Q1(d) (2 marks): Use your Born–Haber cycle from part (c) to calculate a value for the enthalpy of lattice dissociation for magnesium oxide.
June 2011, CHEM5 (old spec), Q1(a)(i) (2 marks): enthalpy of lattice formation for calcium fluoride
June 2011, CHEM5 (old spec), Q1(a)(ii) (1 mark): enthalpy of hydration for fluoride ions (1 mark)
June 2011, CHEM5 (old spec), Q1(b) (2 marks): Explain the interactions between water molecules and fluoride ions when the fluoride ions become hydrated.
June 2011, CHEM5 (old spec), Q1(c) (2 marks): Consider the following data. ΔH / kJ mol–1 Enthalpy of lattice formation for CaF2 –2611 Enthalpy of hydration for Ca2+ ions –1650 Enthalpy of hydration for F– i
January 2011, CHEM5 (old spec), Q1(a) (4 marks): Define the terms enthalpy of atomisation and lattice dissociation enthalpy. Enthalpy of atomisation Lattice dissociation enthalpy
January 2011, CHEM5 (old spec), Q1(b) (3 marks): Use the following data to calculate a value for the lattice dissociation enthalpy of sodium chloride.
January 2011, CHEM5 (old spec), Q1(c)(i) (2 marks): Explain the meaning of the term perfect ionic model.
January 2011, CHEM5 (old spec), Q1(c)(ii) (1 mark): State what you can deduce about the bonding in NaBr from the data in the table. (1 mark)
January 2011, CHEM5 (old spec), Q1(c)(iii) (1 mark): State what you can deduce about the bonding in AgBr from the data in the table. (1 mark)
June 2010, CHEM5 (old spec), Q1(a) (1 mark): Write an equation, including state symbols, for the process that occurs when the calcium fluoride lattice dissociates and for which the enthalpy change is equal
June 2010, CHEM5 (old spec), Q1(b)(iii) (3 marks): Use data from the Tables 1 and 2 to calculate the standard enthalpy of formation for calcium fluoride.
June 2010, CHEM5 (old spec), Q1(c) (2 marks): Explain why the enthalpy of lattice dissociation for calcium fluoride is greater than that for calcium chloride.
June 2010, CHEM5 (old spec), Q1(d)(i) (2 marks): Using data from Table 2, calculate the enthalpy change for this reaction.
January 2010, CHEM5 (old spec), Q4(a) (1 mark): Calculate the bond enthalpy of a Cl–Cl bond. (1 mark)
January 2010, CHEM5 (old spec), Q4(c) (1 mark): Suggest why the electron affinity of chlorine is an exothermic change. (1 mark)
January 2010, CHEM5 (old spec), Q4(d)(i) (3 marks): Complete the diagram by writing the appropriate chemical symbols, with state symbols, on each of the three blank lines. (3 marks)
January 2010, CHEM5 (old spec), Q4(d)(ii) (2 marks): Calculate a value for the enthalpy of lattice dissociation for silver chloride.
January 2010, CHEM5 (old spec), Q4(e)(i) (1 mark): Explain the meaning of the term perfect ionic model. (1 mark)
January 2010, CHEM5 (old spec), Q4(e)(ii) (3 marks): State whether you would expect the value of the theoretical enthalpy of lattice dissociation for silver chloride to be greater than, equal to or less than that
January 2010, CHEM5 (old spec), Q4(e)(iii) (2 marks): Suggest why your answer to part (d) (ii) is greater than the theoretical value for the enthalpy of lattice dissociation for silver chloride. (2 marks)
June 2008, CHM5 (2008 spec), Q8(a) (3 marks): 8 (a) Use these data to calculate the lattice enthalpy of dissociation of sodium chloride and of magnesium chloride. (3 marks)
June 2008, CHM5 (2008 spec), Q8(b) (2 marks): 8 (b) Explain why the lattice enthalpy of dissociation of sodium chloride is less than that of magnesium chloride. (2 marks)
June 2008, CHM5 (2008 spec), Q8(c) (2 marks): 8 (c) Suggest why the enthalpy of hydration of aluminium ions is much more exothermic than that for magnesium ions. (2 marks)
January 2008, CHM1 (2008 spec), Q3(e) (2 marks): (e) Chloride ions are polarised by cations. (i) State the meaning of the term polarised as applied to a Cl– ion. (ii) State a feature of a cation that would cau

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