Thermochemistry: Eduqas A‑Level Chemistry questions

Every Eduqas A-Level Chemistry exam question on C2.2 Thermochemistry, 2016–2025, with its mark scheme and examiner’s report.

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1,513 questions

Q2
June 2025 · Component 1
2 marksC2.2 Thermochemistry
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Q6
June 2025 · Component 1
2 marksC2.2 Thermochemistry
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Q4(b)
June 2025 · AS Component 2
2 marksC2.2 Thermochemistry
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Q9(a)(i)
June 2025 · AS Component 2
1 markC2.2 Thermochemistry
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Q9(a)(ii)
June 2025 · AS Component 2
1 markC2.2 Thermochemistry
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Q9(a)(iii)
June 2025 · AS Component 2
2 marksC2.2 Thermochemistry
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Q9(a)(iv)
June 2025 · AS Component 2
3 marksC2.2 Thermochemistry
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Q9(a)(v)
June 2025 · AS Component 2
1 markC2.2 Thermochemistry
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Q9(a)(vi)
June 2025 · AS Component 2
1 markC2.2 Thermochemistry
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Q9(b)(i)
June 2025 · AS Component 2
2 marksC2.2 Thermochemistry
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Q9(a)(iii)
June 2024 · Component 1
5 marksC2.2 Thermochemistry
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Q13(d)(i)
June 2024 · Component 1
1 markC2.2 Thermochemistry
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Q13(d)(ii)
June 2024 · Component 1
2 marksC2.2 Thermochemistry
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Q10(d)(i)
June 2024 · AS Component 2
2 marksC2.2 Thermochemistry
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Q10(d)(ii)
June 2024 · AS Component 2
1 markC2.2 Thermochemistry
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Q11(a)
June 2024 · AS Component 2
1 markC2.2 Thermochemistry
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Q11(b)
June 2024 · AS Component 2
1 markC2.2 Thermochemistry
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Q11(c)
June 2024 · AS Component 2
1 markC2.2 Thermochemistry
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Q11(d)
June 2024 · AS Component 2
2 marksC2.2 Thermochemistry
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Q11(e)
June 2024 · AS Component 2
3 marksC2.2 Thermochemistry
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All 81 questions on Thermochemistry, as a list

June 2025, Component 1, Q2 (2 marks): Write the equation for the enthalpy of formation of ethanol. [2] Include state symbols.
June 2025, Component 1, Q6 (2 marks): Use the average bond enthalpies listed to calculate the enthalpy change of the reaction shown. [2] H H C C + 3O2 2CO2 + 2H2O H H Bond C H C C C C O O C O O H Av
June 2025, AS Component 2, Q4(b) (2 marks): Write the equation for the standard molar enthalpy change of formation of ammonia. [2]
June 2025, AS Component 2, Q9(a)(i) (1 mark): Give the reason why she accurately measured the volume of the water. [1]
June 2025, AS Component 2, Q9(a)(ii) (1 mark): Give the reason why the temperature of the water was measured for two minutes before adding the sodium nitrate. [1]
June 2025, AS Component 2, Q9(a)(iii) (2 marks): Plot the results on the grid below. [2] 100 2 4 6 8 10 Time / min
June 2025, AS Component 2, Q9(a)(iv) (3 marks): Determine the maximum temperature change by drawing appropriate lines of best fit. [3] Maximum temperature change = °C
June 2025, AS Component 2, Q9(a)(v) (1 mark): Explain why the value determined in part (iv) is a more accurate temperature change than one found using the lowest temperature recorded in the experiment. [1
June 2025, AS Component 2, Q9(a)(vi) (1 mark): The student calculated the enthalpy change to be 19.2 kJ mol−1 The data book value for this enthalpy change is 20.5 kJ mol−1. Express the difference between the
June 2025, AS Component 2, Q9(b)(i) (2 marks): Use this enthalpy change of reaction and the standard enthalpy changes of formation (ΔfH θ) given in the table below to calculate the standard enthalpy change o
June 2024, Component 1, Q9(a)(iii) (5 marks): Propanoic acid reacts with calcium carbonate in an endothermic reaction. I. Complete the equation for this reaction. [2] CH3CH2COOH + CaCO3 H2O + CO2 + II. A st
June 2024, Component 1, Q13(d)(i) (1 mark): Give a reason why the standard enthalpy change of formation for oxygen is 0 kJ mol–1. [1]
June 2024, Component 1, Q13(d)(ii) (2 marks): Calculate the standard enthalpy change for this reaction. [2] ΔHθ = kJ mol–1
June 2024, AS Component 2, Q10(d)(i) (2 marks): State the meaning of the term standard molar enthalpy change of formation of ethanol. [2]
June 2024, AS Component 2, Q10(d)(ii) (1 mark): Give a reason why it is not possible to measure the standard enthalpy change of formation of ethanol directly. [1]
June 2024, AS Component 2, Q11(a) (1 mark): Give a reason why she did not accurately measure the mass of zinc. [1]
June 2024, AS Component 2, Q11(b) (1 mark): Give a reason why the temperature of the solution was measured for 3 minutes before adding zinc. [1]
June 2024, AS Component 2, Q11(c) (1 mark): Give a reason why the temperature of the solution was measured for a period of time after all the copper(II) sulfate had reacted. [1]
June 2024, AS Component 2, Q11(d) (2 marks): Plot the student’s results on the grid below. [2] Temperature / °C 80 70 60 50 40 30 20 0 2 4 6 8 10 Time / minutes
June 2024, AS Component 2, Q11(e) (3 marks): Determine the maximum temperature change by drawing appropriate lines of best fit. [3] Maximum temperature change = °C
June 2024, AS Component 2, Q11(f) (2 marks): State whether the lines of best fit on the graph are good enough to be extrapolated with confidence. Explain your answer. [2]
June 2024, AS Component 2, Q11(h) (4 marks): Calculate the molar enthalpy change for this reaction, in kJ mol−1. Give your answer to the appropriate number of significant figures. [4] ΔH = kJ mol−1
Autumn 2021, Component 1, Q6 (2 marks): Write an equation to show the reaction that represents the standard enthalpy change of formation of ethanol, ΔfHθ (C2H5OH). You should include state symbols. [
Autumn 2021, Component 1, Q11(d)(ii) (1 mark): State why the standard enthalpy changes of formation for copper and chlorine are zero. [1]
Autumn 2021, Component 1, Q12(a)(ii) (2 marks): In the second step, nitric oxide is converted into nitrogen dioxide, NO2. 2NO2(g) ΔHθ = −114 kJ mol–1 2NO(g) + O2(g) The standard enthalpy change of formation o
Autumn 2021, Component 1, Q12(a)(iii) (9 marks): The final step is shown below. 2HNO3(aq) + NO(g) ΔHθ = −117 kJ mol–1 3NO2(g) + H2O(l) I. Use oxidation states to show that this is a disproportionation reaction
Autumn 2021, Component 3, Q1(a)(i) (2 marks): Write the equation that represents the molar enthalpy change of combustion (∆cH) of propan-1-ol. [2]
Autumn 2021, Component 3, Q1(a)(ii) (4 marks): Describe how you would determine the enthalpy change of combustion of propan-1-ol. State what measurements you would need to make and outline how you would use
Autumn 2021, Component 3, Q1(b)(i) (2 marks): Plot a graph of heat evolved against number of moles of ethanol in the mixture. [2] Number of moles of ethanol in the mixture
Autumn 2021, Component 3, Q1(b)(ii) (1 mark): Describe the trend in the graph. [1]
Autumn 2021, Component 3, Q1(b)(iii) (1 mark): Calculate the enthalpy change of combustion of propan-1-ol in kJ mol–1. [1] Enthalpy of combustion = kJ mol–1
Autumn 2021, Component 3, Q1(b)(iv) (2 marks): A mixture of ethanol and propan-1-ol containing a total of 0.010 mol produced 15.35 kJ of heat on combustion. Calculate the mass of ethanol present in this mixt
Autumn 2021, Component 3, Q1(b)(v) (2 marks): On the grid on page 5, sketch the graph that would be obtained if the propan-1-ol were replaced with butan-1-ol. [2]
Autumn 2020, Component 1, Q9(d)(iv) (3 marks): The reaction between methyllithium and water is exothermic. The enthalpy change of the reaction is –198 kJ mol–1. Calculate the expected temperature rise when 0
Autumn 2020, Component 1, Q11(d)(i) (3 marks): Calculate the bond energy of the C―O bond in methanol. [3] Bond Bond energy / kJ mol–1 C H 414 O O 498 O H 464 C O 803 Bond energy = ……… ………………… kJ mol–1
Autumn 2020, Component 1, Q11(d)(ii) (1 mark): Give a reason why the value calculated in part (i) may not precisely match the actual energy of this C―O bond. [1]
Autumn 2020, Component 1, Q11(d)(iii) (3 marks): The standard enthalpy change of combustion of methanol has a value of –715 kJ mol–1. Give reasons why this value is very different from the value associated wit
Autumn 2020, AS Component 2, Q7(b)(i) (2 marks): Write the equation to represent the standard molar enthalpy change of formation of ethanol. [2]
Autumn 2020, AS Component 2, Q7(b)(ii) (4 marks): The equation for its combustion is given below. C2H5OH + 3O2 2CO2 + 3H2O I. A student calculated the enthalpy change for this reaction as –1031 kJ mol–1 using t
Autumn 2020, AS Component 2, Q10(a)(i) (6 marks): Describe how you would carry out an experiment to determine the enthalpy change of the reaction between magnesium oxide and hydrochloric acid. Your answer shoul
Autumn 2020, AS Component 2, Q10(a)(ii) (4 marks): A student carried out this experiment and calculated the enthalpy change of reaction to be –115 kJ mol–1 He used 0.900 g of magnesium oxide and 50.0 cm3 of 2.00
June 2019, Component 1, Q13(a)(ii) (1 mark): The enthalpy change value given above is not the standard enthalpy change of formation for ammonia. Give one reason why this is not the standard enthalpy change
June 2019, Component 1, Q13(b)(i) (1 mark): State what information these values provide about the stability of these molecules. [1]
June 2019, Component 1, Q13(b)(ii) (7 marks): One method of producing hydrazine is to oxidise ammonia using an appropriate oxidising agent, such as hydrogen peroxide. 2NH3(g) + H2O2(l) NH2NH2(l) + 2H2O(l) Δ
June 2019, Component 3, Q1(a) (2 marks): The value of ∆T obtained was much lower than expected. Briefly indicate three possible sources of error in the ∆T measurement from the information provided. [2]
June 2019, Component 3, Q1(b) (2 marks): The student measured a 10.0 °C temperature change on mixing both solids and used this value to calculate the enthalpy change of reaction as +10.5 kJ mol–1. Calc
June 2019, Component 3, Q1(c) (1 mark): Deduce the maximum temperature change if the experiment were repeated using 100 g of water rather than the 50 g used in the first experiment, with all other fac
June 2019, AS Component 2, Q5(a) (1 mark): State Hess’s Law. [1]
June 2019, AS Component 2, Q5(b) (1 mark): Determine the value of ΔH, in kJ mol–1, in the energy cycle below. [1] –125.1 kJ mol–1 C3H6(g) + H2(g) C3H8(g) ΔH –104.7 kJ mol–1 3C(s) + 4H2(g) ΔH = kJ mol–1
June 2019, AS Component 2, Q9(a) (1 mark): The student said that it is not necessary to ensure that the hydrogen peroxide and the iron(III) nitrate are at the same temperature before addition. Is she cor
June 2019, AS Component 2, Q9(c) (4 marks): Calculate the value, in kJ mol–1, for the enthalpy change of reaction for the decomposition of hydrogen peroxide. Give your answer to an appropriate number of s
June 2019, AS Component 2, Q9(d) (1 mark): State why she accurately measured the volume of the catalyst. [1]
June 2019, AS Component 2, Q9(e) (1 mark): State how the student would know that the decomposition reaction had finished. [1]
June 2019, AS Component 2, Q9(f) (4 marks): Suggest two improvements that would make the experiment more accurate. Justify both improvements. [4] 1. 2.
June 2019, AS Component 2, Q10(c)(i) (3 marks): The equation for its combustion is given below. C2H5OH + 3O2 2CO2 + 3H2O Use the average bond enthalpy values given in the table below to calculate the enthalpy
June 2019, AS Component 2, Q12(g) (2 marks): He used the following apparatus to measure the volume of hydrogen produced over time. gas syringe hydrochloric acid magnesium strip The experiment was carried o
June 2018, Component 1, Q14(c)(i) (1 mark): Give the temperature and pressure used as standard conditions. [1]
June 2018, Component 1, Q15(c)(i) (2 marks): Identify two errors that the student has made. [2]
June 2018, Component 1, Q15(c)(ii) (4 marks): The student found the following data in a reference source. He wanted to calculate the most accurate value for the enthalpy change for his reaction. Standard en
June 2018, Component 1, Q15(c)(iii) (5 marks): The student decided to compare his value with one obtained experimentally. He used the apparatus and method given below. thermometer conical flask appropriate v
June 2018, AS Component 2, Q7(b) (3 marks): Propane is a constituent of liquefied petroleum gas (LPG). Propane burns in air to form carbon dioxide and water. The equation for the reaction is as follows. H
June 2018, AS Component 2, Q9(a) (4 marks): Calculate a value for the enthalpy change of combustion of pentan-2-ol in kJ mol–1. [4] ΔcH = kJ mol–1
June 2018, AS Component 2, Q9(b)(i) (1 mark): Each reading on the thermometer is accurate to ±0.1 °C. Calculate the percentage error in the temperature difference recorded. [1] Percentage error = %
June 2018, AS Component 2, Q9(b)(ii) (2 marks): Suggest how, using the same apparatus, the experiment could be improved to reduce this percentage error. Explain your answer. [2]
June 2018, AS Component 2, Q9(c)(i) (1 mark): Suggest an experimental improvement that would reduce error due to heat loss. [1]
June 2018, AS Component 2, Q9(c)(ii) (1 mark): Suggest one reason, other than heat loss, why the value obtained for the enthalpy change of combustion is smaller than the theoretical value. [1]
June 2018, AS Component 2, Q9(d)(i) (1 mark): Write an equation for the complete combustion of C5H11OH. [1]
June 2018, AS Component 2, Q9(d)(ii) (2 marks): Use the values in the table and the equation in part (i) to calculate the standard enthalpy change of combustion, ΔcHθ, of 2-methylbutan-2-ol. [2] ΔcHθ = kJ mol
June 2018, AS Component 2, Q9(d)(iii) (1 mark): State why O2(g) has a value of zero for its standard enthalpy change of formation, ΔfHθ. [1]
June 2017, AS Component 2, Q10(a)(i) (1 mark): The first experiment was to find the molar enthalpy change, ΔH1, for the reaction MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(l) ΔH1 was calculated to be –115 kJ mol–1. G
June 2017, AS Component 2, Q10(a)(ii) (6 marks): The second experiment was to find the molar enthalpy change, ΔH2, for the reaction MgCO3(s) + 2HCl(aq) MgCl2(aq) + H2O(l) + CO2(g) The following values were rec
June 2017, AS Component 2, Q10(a)(iii) (2 marks): The hydrochloric acid used in these experiments could be measured using either a volumetric pipette or a measuring cylinder. Give one practical advantage of usi
June 2017, AS Component 2, Q10(a)(iv) (1 mark): Each reading on the thermometer is accurate to ± 0.1 °C. Calculate the percentage error in the temperature rise recorded. [1] Percentage error = %
June 2017, AS Component 2, Q10(a)(v) (2 marks): A Hess cycle connecting ΔrH to ΔH1 and ΔH2 is shown below. ΔrH MgO(s) + CO2(g) MgCO3(s) 2HCl(aq) ΔH1 ΔH2 2HCl(aq) MgCl2(aq) + H2O(l) + CO2(g) Calculate the valu
June 2017, AS Component 2, Q10(b) (2 marks): The equation for the reaction between hydrazine and nitrogen dioxide is as follows. 2N2H4(l) + 2NO2(g) 3N2(g) + 4H2O(l) ΔH = −1313 kJ mol–1 Using this value and
June 2016, AS Component 2, Q9(a)(i) (4 marks): Calculate the molar enthalpy change of solution of ammonium nitrate, in kJ mol−1, giving your answer to an appropriate number of significant figures. [4] ΔH = k
June 2016, AS Component 2, Q9(a)(ii) (4 marks): Kathryn’s results gave a lower value than the literature value. Suggest two improvements to her method and explain how they would lead to a more accurate value.
June 2016, AS Component 2, Q9(a)(iii) (2 marks): During the experiment the balance broke before Kathryn could weigh the water. Describe how else she could precisely measure 50.0 g of water. Explain why this me
June 2016, AS Component 2, Q9(b)(i) (2 marks): Calculate the standard enthalpy change of reaction using the standard enthalpy change of formation values. [2] ΔHθ = kJ mol−1
June 2016, AS Component 2, Q9(b)(ii) (3 marks): Calculate the standard enthalpy change of reaction using the average bond enthalpy values. [3] ΔHθ = kJ mol−1
June 2016, AS Component 2, Q9(b)(iii) (1 mark): Which calculation leads to the more accurate value? Justify your answer. [1]

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