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Oxidation, reduction and redox equations: AQA A‑Level Chemistry questions

Every AQA A-Level Chemistry exam question on 3.1.7 Oxidation, reduction and redox equations, 2016–2025, with its mark scheme and examiner’s report.

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2,301 questions

  1. Q03.6

    June 2025 · Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2025 Paper 1, question 03.6: Give an equation for the reaction between C2O42– ions and MnO4– ions in acidic solution. [1 mark]

  2. Q03.8

    June 2025 · Paper 1

    7 marks3.1.2 Amount of substance3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2025 Paper 1, question 03.8: Calculate the Mr of M2[Cu(C2O4)2(H2O)2] Identify M. [7 marks] Mr of M2[Cu(C2O4)2(H2O)2] Identity of M

  3. Q05.2

    June 2025 · Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2025 Paper 1, question 05.2: Bromine reacts with fluorine to form BrF3 Determine the oxidation state of bromine and of fluorine in BrF3 [1 mark] Oxidation state of Br Oxidation state of F

  4. Q02.5

    June 2025 · AS Paper 1

    2 marks3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2025 AS Paper 1, question 02.5: When gently warmed in aqueous solution, NaClO reacts to form NaCl and NaClO3 Complete the equation to ensure that it is correctly balanced. Deduce the oxidation

  5. Q02.6

    June 2025 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2025 AS Paper 1, question 02.6: Deduce the half-equation, in acidic conditions, for the conversion of ClO3– into Cl– [1 mark]

  6. Q20

    June 2025 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2025 AS Paper 1, question 20: Which statement about SO2 acting as a reducing agent is correct? [1 mark] A SO2 gains electrons and the oxidation state of sulfur decreases. B SO2 gains electro

  7. Q05.3

    June 2024 · Paper 1

    3 marks3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2024 Paper 1, question 05.3: In acidic conditions, ClO3 – ions oxidise Cl– ions to form Cl2 Deduce a half-equation for the oxidation of Cl– to Cl2 Deduce a half-equation for the reduction o

  8. Q06.4

    June 2024 · Paper 1

    4 marks3.1.7 Oxidation, reduction and redox equations3.1.2 Amount of substance
    The whole paper ↗
    June 2024 Paper 1, question 06.4: 0.151 g of impure NH4VO3 is added to dilute sulfuric acid to form a solution containing aqueous VO2+ ions. All the VO3– ions are converted to VO2+ ions. These V

  9. Q02.3

    June 2024 · AS Paper 1

    2 marks3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2024 AS Paper 1, question 02.3: The reaction of calcium with water is a redox reaction. Explain, in terms of oxidation states, why this reaction involves both oxidation and reduction. [2 marks

  10. Q09.1

    June 2024 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2024 AS Paper 1, question 09.1: State, in terms of electrons, the meaning of the term oxidising agent. [1 mark]

  11. Q09.2

    June 2024 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2024 AS Paper 1, question 09.2: Give a half-equation to show the oxidation of copper to copper(II) ions. [1 mark]

  12. Q09.3

    June 2024 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2024 AS Paper 1, question 09.3: Give a half-equation to show the reduction of NO3– ions in acidic solution to NO2 [1 mark]

  13. Q09.4

    June 2024 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2024 AS Paper 1, question 09.4: Use your answers to Question 09.2 and Question 09.3 to deduce an overall equation for the reduction of NO3– ions by copper. [1 mark] Section B Answer all questi

  14. Q01.3

    June 2023 · Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2023 Paper 1, question 01.3: Suggest why the oxidation state of chromium is zero in Cr(PF3)6 [1 mark]

  15. Q01.4

    June 2023 · Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2023 Paper 1, question 01.4: Deduce the oxidation state of chromium in [Cr(NH3)4Cl2]Cl [1 mark]

  16. Q14

    June 2023 · Paper 3

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2023 Paper 3, question 14: In which oxide is the named element in its highest oxidation state? [1 mark] A chlorine in ClO2 B magnesium in MgO C nitrogen in N2O4 D sulfur in SO2

  17. Q16

    June 2023 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2023 AS Paper 1, question 16: In which species is chlorine in its highest oxidation state? [1 mark] A ClF2– B ClO4– C ClO2 D ClF3

  18. Q17

    June 2023 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2023 AS Paper 1, question 17: Which statement about this redox reaction is correct? 3 Sn2+(aq) + Cr2O72– (aq) + 2 H+(aq) → 2 Cr3+(aq) + 3 SnO2(s) + H2O(l) [1 mark] A Sn2+ is the oxidising ag

  19. Q18

    June 2023 · AS Paper 1

    1 mark3.1.7 Oxidation, reduction and redox equations
    The whole paper ↗
    June 2023 AS Paper 1, question 18: Which incomplete half-equation is balanced by adding two H+ ions and one electron to the left-hand side? [1 mark] A CH3CHO → CH3CH2OH B VO2+ → V3+ + H2O C HNO2

  20. Q03.1

    June 2022 · Paper 1

    5 marks3.1.7 Oxidation, reduction and redox equations3.1.2 Amount of substance
    The whole paper ↗
    June 2022 Paper 1, question 03.1: Give an ionic equation for the reaction between potassium manganate(VII) and acidified hydrogen peroxide. Calculate the concentration, in mol dm–3, of hydrogen
All 66 questions on Oxidation, reduction and redox equations, as a list
  1. June 2025, Paper 1, Q03.6 (1 mark): Give an equation for the reaction between C2O42– ions and MnO4– ions in acidic solution. [1 mark]
  2. June 2025, Paper 1, Q03.8 (7 marks): Calculate the Mr of M2[Cu(C2O4)2(H2O)2] Identify M. [7 marks] Mr of M2[Cu(C2O4)2(H2O)2] Identity of M
  3. June 2025, Paper 1, Q05.2 (1 mark): Bromine reacts with fluorine to form BrF3 Determine the oxidation state of bromine and of fluorine in BrF3 [1 mark] Oxidation state of Br Oxidation state of F
  4. June 2025, AS Paper 1, Q02.5 (2 marks): When gently warmed in aqueous solution, NaClO reacts to form NaCl and NaClO3 Complete the equation to ensure that it is correctly balanced. Deduce the oxidation
  5. June 2025, AS Paper 1, Q02.6 (1 mark): Deduce the half-equation, in acidic conditions, for the conversion of ClO3– into Cl– [1 mark]
  6. June 2025, AS Paper 1, Q20 (1 mark): Which statement about SO2 acting as a reducing agent is correct? [1 mark] A SO2 gains electrons and the oxidation state of sulfur decreases. B SO2 gains electro
  7. June 2024, Paper 1, Q05.3 (3 marks): In acidic conditions, ClO3 – ions oxidise Cl– ions to form Cl2 Deduce a half-equation for the oxidation of Cl– to Cl2 Deduce a half-equation for the reduction o
  8. June 2024, Paper 1, Q06.4 (4 marks): 0.151 g of impure NH4VO3 is added to dilute sulfuric acid to form a solution containing aqueous VO2+ ions. All the VO3– ions are converted to VO2+ ions. These V
  9. June 2024, AS Paper 1, Q02.3 (2 marks): The reaction of calcium with water is a redox reaction. Explain, in terms of oxidation states, why this reaction involves both oxidation and reduction. [2 marks
  10. June 2024, AS Paper 1, Q09.1 (1 mark): State, in terms of electrons, the meaning of the term oxidising agent. [1 mark]
  11. June 2024, AS Paper 1, Q09.2 (1 mark): Give a half-equation to show the oxidation of copper to copper(II) ions. [1 mark]
  12. June 2024, AS Paper 1, Q09.3 (1 mark): Give a half-equation to show the reduction of NO3– ions in acidic solution to NO2 [1 mark]
  13. June 2024, AS Paper 1, Q09.4 (1 mark): Use your answers to Question 09.2 and Question 09.3 to deduce an overall equation for the reduction of NO3– ions by copper. [1 mark] Section B Answer all questi
  14. June 2023, Paper 1, Q01.3 (1 mark): Suggest why the oxidation state of chromium is zero in Cr(PF3)6 [1 mark]
  15. June 2023, Paper 1, Q01.4 (1 mark): Deduce the oxidation state of chromium in [Cr(NH3)4Cl2]Cl [1 mark]
  16. June 2023, Paper 3, Q14 (1 mark): In which oxide is the named element in its highest oxidation state? [1 mark] A chlorine in ClO2 B magnesium in MgO C nitrogen in N2O4 D sulfur in SO2
  17. June 2023, AS Paper 1, Q16 (1 mark): In which species is chlorine in its highest oxidation state? [1 mark] A ClF2– B ClO4– C ClO2 D ClF3
  18. June 2023, AS Paper 1, Q17 (1 mark): Which statement about this redox reaction is correct? 3 Sn2+(aq) + Cr2O72– (aq) + 2 H+(aq) → 2 Cr3+(aq) + 3 SnO2(s) + H2O(l) [1 mark] A Sn2+ is the oxidising ag
  19. June 2023, AS Paper 1, Q18 (1 mark): Which incomplete half-equation is balanced by adding two H+ ions and one electron to the left-hand side? [1 mark] A CH3CHO → CH3CH2OH B VO2+ → V3+ + H2O C HNO2
  20. June 2022, Paper 1, Q03.1 (5 marks): Give an ionic equation for the reaction between potassium manganate(VII) and acidified hydrogen peroxide. Calculate the concentration, in mol dm–3, of hydrogen
  21. June 2022, Paper 1, Q03.3 (1 mark): Give the oxidation state of oxygen in hydrogen peroxide. [1 mark]
  22. June 2022, Paper 3, Q10 (1 mark): Which of these oxidation states is correct? [1 mark] A Chlorine in Cl2 is –1 B Chromium in K2Cr2O7 is +7 C Fluorine in F2O is –1 D Hydrogen in NaH is +1
  23. June 2022, AS Paper 1, Q06.1 (1 mark): State, in terms of electrons, the meaning of the term oxidising agent. [1 mark]
  24. June 2022, AS Paper 1, Q06.2 (2 marks): Give a half-equation for the oxidation of iodide ions to iodine. Deduce the half-equation to show the reduction process in this reaction. [2 marks] Oxidation ha
  25. June 2022, AS Paper 1, Q19 (1 mark): In which of these substances is oxygen in the highest oxidation state? [1 mark] A OF2 B H2O C O2 D H2O2
  26. November 2021, Paper 1, Q09.4 (1 mark): In some lithium cells, lithium perchlorate (LiClO4) is used as the electrolyte. Deduce the oxidation state of chlorine in LiClO4 [1 mark]
  27. November 2021, Paper 3, Q21 (1 mark): Which equation does not show the reduction of a transition metal? [1 mark] A TiCl4 + 2 Mg → Ti + 2 MgCl2 B 2 FeCl3 + 2 KI → 2 FeCl2 + 2 KCl + I2 C MnO2 + 4 HCl
  28. November 2021, AS Paper 1, Q03.1 (1 mark): State, in terms of electrons, the meaning of the term oxidising agent. [1 mark]
  29. November 2021, AS Paper 1, Q03.2 (3 marks): Cr2O72– can oxidise SO32– in acidic conditions to form Cr3+ and SO42– Deduce a half-equation for the oxidation of SO32– to SO42– Deduce a half-equation for the
  30. November 2021, AS Paper 1, Q16 (1 mark): Which compound contains a chlorine atom with an oxidation state of +4? [1 mark] A KClO4 B CCl4 C ClO2 D ClO2F
  31. November 2020, Paper 1, Q08.1 (7 marks): Use all the information given to calculate the percentage by mass of NaClO in the original bleach solution. Give your answer to 3 significant figures. [7 marks]
  32. November 2020, Paper 3, Q01.3 (2 marks): Modern diesel vehicles use diesel exhaust fluids, such as AdBlue, to decrease emissions of oxides of nitrogen. AdBlue reacts with water in the hot exhaust gases
  33. November 2020, Paper 3, Q11 (1 mark): In which conversion is the metal reduced? [1 mark] A Cr2O72– → CrO42– B MnO42– → MnO4– C TiO2 → TiO32– D VO3– → VO2+
  34. November 2020, AS Paper 1, Q13 (1 mark): NO2− ions can be reduced in acidic solution to NO How many electrons are gained when each NO2− ion is reduced? [1 mark] A 1 B 2 C 3 D 4
  35. November 2020, AS Paper 1, Q21 (1 mark): Which compound contains chlorine in an oxidation state of +1? [1 mark] A Cl2O B KClO3 C ClF3 D CCl4
  36. June 2019, Paper 1, Q03.5 (1 mark): Complete the equation for the formation of arsenic hydride. [1 mark] As2O3 + Zn + HNO3 → AsH3 + Zn(NO3)2 + H2O
  37. June 2019, Paper 3, Q05.1 (1 mark): Give the equation for the reaction between iron and sulfuric acid. [1 mark]
  38. June 2019, Paper 3, Q05.3 (1 mark): Give the overall ionic equation for the oxidation of Fe2+ by manganate(VII) ions, in acidic conditions. [1 mark]
  39. June 2019, AS Paper 1, Q03.4 (1 mark): Deduce the oxidation state of chromium in the Cr2O7 2– ion. [1 mark]
  40. June 2019, AS Paper 1, Q03.5 (1 mark): Iodide ions can be oxidised to iodine using Cr2O7 2– ions. Deduce a half-equation to show the oxidation of iodide ions to iodine. State symbols are not required
  41. June 2019, AS Paper 1, Q03.6 (1 mark): Deduce a half-equation for the conversion in acidic solution of Cr2O7 2– ions to Cr3+ ions. State symbols are not required. [1 mark]
  42. June 2019, AS Paper 1, Q03.7 (1 mark): Use your answers from questions 03.5 and 03.6 to deduce the overall redox equation for the reaction between iodide ions and acidified Cr2O7 2– ions. State symbo
  43. June 2019, AS Paper 1, Q15 (1 mark): Which equation does not represent a redox reaction? [1 mark] A Mg + 2 HCl → MgCl2 + H2 B CH4 + 2 O2 → CO2 + 2 H2O C Fe + CuSO4 → FeSO4 + Cu D CuO + 2 HCl → CuCl
  44. June 2018, Paper 1, Q03.5 (1 mark): Deduce the change in oxidation state of nitrogen, when NH3 is oxidised to NO [1 mark]
  45. June 2018, Paper 1, Q03.6 (1 mark): When ammonia reacts with oxygen, nitrous oxide (N2O) can be produced instead of NO Give an equation for this reaction. [1 mark]
  46. June 2018, AS Paper 1, Q07.1 (1 mark): Deduce the oxidation state of chlorine in HClO and the oxidation state of chlorine in HCl [1 mark] Oxidation state of chlorine in HClO Oxidation state of chlori
  47. June 2018, AS Paper 1, Q07.2 (2 marks): Give two half-equations to show the oxidation and reduction processes that occur in this redox reaction. [2 marks] Oxidation half-equation Reduction half-equati
  48. June 2017, Paper 1, Q10.1 (2 marks): Deduce the oxidation state of nitrogen in NO3 − and in NO [2 marks] Nitrogen in NO3 − Nitrogen in NO
  49. June 2017, Paper 1, Q11.1 (8 marks): A white solid is a mixture of sodium ethanedioate (Na2C2O4), ethanedioic acid dihydrate (H2C2O4.2H2O) and an inert solid. A volumetric flask contained 1.90 g of
  50. June 2017, AS Paper 1, Q08.1 (2 marks): Give the oxidation state of nitrogen in the following species. [2 marks NO2 − NO
  51. June 2017, AS Paper 1, Q08.2: Write a half-equation for the conversion of NO2 − in an acidic solution into NO [1 mar
  52. June 2017, AS Paper 1, Q08.3 (1 mark): Write a half-equation for the conversion of I− into I2 [1 mark
  53. June 2017, AS Paper 1, Q08.4 (1 mark): Write an overall ionic equation for the reaction of NO2 − in an acidic solution with I− [1 mark
  54. June 2017, AS Paper 1, Q08.5 (1 mark): State the role of NO2 − in the reaction with I− [1 mark
  55. June 2017, AS Paper 1, Q08.6 (4 marks): In aqueous solution, nitrite ions react with acidified chlorate(V) ions according to the equation 2ClO3 − + 5NO2 − + 2H+ → Cl2 + 5NO3 − + H2O A 25.0 cm3 sample
  56. June 2017, AS Paper 1, Q20: Which of these is not a redox reaction? [1 mar A Cu2O + H2SO4 → CuSO4 + Cu + H2O B MgO + 2HCl → MgCl2 + H2O C SnCl2 + HgCl2 → Hg + SnCl4 D MnO2 + 4HCl → MnCl2 +
  57. June 2016, AS Paper 1, Q08.1 (1 mark): Write a half-equation for the oxidation of chloride ions. [1 mark
  58. June 2016, AS Paper 1, Q08.2 (1 mark): Write a half-equation for the reduction of chlorate(l) ions to chlorine in acidic conditions. [1 mark
  59. June 2016, AS Paper 1, Q08.3 (1 mark): Write an overall equation for the redox reaction of chlorate(I) ions with hydrochloric acid. [1 mark
  60. June 2016, AS Paper 1, Q08.4 (3 marks): A solution of sodium chlorate(l) was added to a colourless solution of potassium iodide. Suggest what is observed. Explain the reaction that leads to this obser
  61. June 2016, AS Paper 1, Q11: Which species contains an element with an oxidation state of +4? [1 mar A NO2 + B ClO3 − C H2SO3 D PCl5
  62. June 2016, AS Paper 1, Q16 (1 mark): In the balanced equation the mole ratio for sulfuric acid to water is [1 mark] A 1 : 4 B 1 : 2 C 4 : 7 D 4 : 9
  63. June 2016, AS Paper 1, Q17 (1 mark): What is the reducing agent in this reaction? [1 mark A H+ B C2O4 2− C K+ D Cr2O7 2−
  64. Specimen, Paper 1, Q07.5 (6 marks): Oxidation state =
  65. Specimen, Paper 3, Q16: In which reaction is hydrogen acting as an oxidising agent? [1 mar A Cl2 + H2 2HCl B (CH3)2CO + H2 (CH3)2CHOH C N2 + 3H2 2NH3 D 2Na + H2 2NaH 1 6
  66. Specimen, Paper 3, Q17: In which reaction is the metal oxidised? [1 mar A 2Cu2+ + 4I – 2CuI + I2 B [Fe(H2O)6]3+ + Cl – [Fe(H2O)5(Cl)]2+ + H2O C [CoCl4]2– + 6H2O [Co(H2O)6]2+ + 4Cl – D

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