plumiEntropy changes in changes of state, dissolving and reactions: Edexcel International A Level Chemistry questions
Edexcel International A Level Chemistry past-paper questions on 12.A.2 Entropy changes in changes of state, dissolving and reactions, 2019–2025, with mark schemes and examiner’s reports where available.
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Q15(d)(ii)
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All 16 questions on Entropy changes in changes of state, dissolving and reactions, as a list
- June 2025, Unit 5, Q15(d)(ii) (2 marks): Explain, by considering the equation shown, why this process is thermodynamically feasible. Pt(Cl)2(NH3)2 + DNA → [Pt(NH3)2(DNA)] 2+ + 2Cl − (2)
- January 2025, Unit 4, Q19(a) (2 marks): Give two reasons why this reaction is thermodynamically feasible when considering the entropy of the system. (2)
- October 2024, Unit 5, Q18(d)(i) (1 mark): Give a reason, by referring to the equation, why the formation of the diamine complex from the aqueous complex ion is thermodynamically favoured. (1)
- June 2024, Unit 4, Q15(a)(ii) (2 marks): The entropy change of the system, ΔSsystem , for Reaction 1 is –43.8 J K–1 mol–1. Suggest, with reference to the equation, why ΔSsystem for this reaction is neg
- June 2024, Unit 5, Q16(b)(ii) (2 marks): Explain, using a balanced equation, why the formation of the dimethyldithiocarbamate complex from an aqueous solution of nickel ions is thermodynamically feasib
- January 2024, Unit 4, Q4 (1 mark): The equations for three reactions involving hydrogen are shown. N2(g) + 3H2(g) → 2NH3(g) J N2(g) + 2H2(g) → N2H4(l) K I2(s) + H2(g) → 2HI(g) L What is the order
- October 2023, Unit 5, Q19(e) (2 marks): Ethanedioate ligands react with iron(II) ions in aqueous solution. 2− → [Fe(C2O4)2 (H2O)2]2− + 4H2O [Fe(H2O)6]2+ + 2C2O4 Explain, in terms of entropy, why this
- January 2023, Unit 4, Q4 (1 mark): Which graph shows the entropy of a substance as it changes state from solid to liquid to gas? Graph 1 Graph 2 Entropy Entropy Temperature Temperature Graph 3 Gr
- January 2023, Unit 4, Q5 (1 mark): Two flasks, P and Q, are connected by a tube fitted with a tap. P Q Flask P contains argon gas and flask Q is in vacuum. Assume argon behaves as an ideal gas an
- October 2022, Unit 4, Q17(a)(iii) (2 marks): Explain why the entropy change of the system, ΔSsystem , is greater for Reaction 1 than for Reaction 2. (2)
- October 2022, Unit 5, Q23(e)(ii) (2 marks): Explain why the salen ligand complex of the Ni2+ ion is much more stable than the aqua complex of the same ion. (2)
- June 2022, Unit 5, Q15(d) (2 marks): The concentration of nickel(II) ions, Ni2+(aq), can be determined by forming a complex with the ligand dimethylglyoxime, C4H8N2O2 . [Ni(H2O)6]2+ + 2C4H8N2O2 + 2
- October 2021, Unit 4, Q3 (1 mark): Ammonium nitrate is very soluble in water. −(aq) ∆H = +25.8 kJ mol−1 NH4NO3(s) + aq → NH4 +(aq) + NO3 What is the best explanation for this? A all ammonium salt
- June 2021, Unit 4, Q20(c) (3 marks): Draw a sketch of entropy against temperature for water to illustrate the entropy changes as temperature increases, including when water changes state. A scale i
- October 2020, Unit 4, Q19(a)(ii) (2 marks): Explain, using ideas about disorder, whether the sign of your answer to (a)(i) is as expected. (2)
- January 2020, Unit 4, Q7 (1 mark): Which of these changes has the largest increase in the entropy of the system? A H2O(s) → H2O(l) B Hg(l) → Hg(g) C H2O(l) + HCl(g) → H3O+(aq) + Cl–(aq) D C(graph
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