plumiIon formation and half-equations: Edexcel International A Level Chemistry questions
Edexcel International A Level Chemistry past-paper questions on 8.A.4 Ion formation and half-equations, 2019–2025, with mark schemes and examiner’s reports where available.
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Q15(c)(ii)
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All 24 questions on Ion formation and half-equations, as a list
- June 2025, AS Unit 2, Q15(c)(ii) (1 mark): The half-equation for the oxidation of iodide ions is shown. 2I– → I2 + 2e– The half-equation for the reduction of concentrated sulfuric acid to hydrogen sulfid
- June 2025 (A), Unit 5, Q16(d)(i) (1 mark): Suggest the half‑equation for the reduction of NO2 – to NO under acidic conditions. State symbols are not required. (1)
- June 2025 (A), Unit 5, Q16(d)(ii) (1 mark): Derive the equation for the reduction of nitrate(III) ions by iodide ions, using your answer to (d)(i). State symbols are not required. (1)
- January 2025, AS Unit 2, Q17(a)(ii) (1 mark): Write the ionic half-equation for the reduction. (1)
- January 2025, AS Unit 2, Q17(a)(iii) (1 mark): Write the ionic half-equation for the oxidation. (1)
- January 2025, Unit 5, Q20(a)(i) (2 marks): Write the equation for Reaction 1. Use the half‑equations from page 10 of your Data Booklet. State symbols are not required. (2)
- October 2024, AS Unit 2, Q20(c)(i) (1 mark): Give the overall equation when the cell is being used. State symbols are not required. (1)
- January 2024, AS Unit 3, Q3(c)(i) (2 marks): Write half‑equations for each of these changes. State symbols are not required. (2) Oxidation of iodide ions: Reduction of hydrogen peroxide under acidic condit
- January 2024, AS Unit 3, Q3(c)(ii) (1 mark): Write the overall equation for the reaction between iodide ions and hydrogen peroxide solution under acidic conditions. State symbols are not required. (1)
- October 2023, AS Unit 2, Q6 (1 mark): What is the value of n in the half‑equation shown? O2(g) + 2H2O(l) + ne– → nOH–(aq) A 2 B 3 C 4 D 5
- June 2023, Unit 5, Q21(b)(ii) (2 marks): Deduce the ionic half-equations for this reaction. State symbols are not required. (2)
- June 2023, Unit 5, Q21(b)(iii) (1 mark): Complete the equation for this reaction by adding the stoichiometric coefficients. (1) Hg(l) + HNO3(aq) → Hg(NO3)2(aq) + NO(g) + H2O(l)
- January 2023, Unit 5, Q18(d)(ii) (2 marks): Write the equation for the reaction between manganate(VII) ions and vanadium(III) ions in acidic solution. State symbols are not required. (2)
- January 2022, AS Unit 2, Q14 (1 mark): Two half‑equations for a reaction are shown. Cu → Cu2+ + 2e− − + 4H+ + 3e− → NO + 2H2O NO3 What is the overall ionic equation for this reaction? A Cu + NO3 − +
- January 2022, Unit 5, Q13(b)(i) (1 mark): Complete the half‑equation. (1) AsH3 → As
- October 2021, AS Unit 2, Q10(a) (1 mark): What values of x, y and z are needed to balance the equation? (1) x y z A 5 6 8 B 10 3 4 C 5 3 8 D 10 6 4
- October 2021, Unit 5, Q18(e) (2 marks): Write the ionic equation for the reaction of complex ion C with chlorine to form complex ion D. (2)
- October 2021, Unit 5, Q20(c)(iii) (2 marks): Write the overall ionic equation for the titration reaction using your answer to (ii) and the relevant half‑equations from the list below. (2) TiO2+ + 2H+ + e
- October 2021, Unit 6, Q1(d)(i) (1 mark): Copper and zinc both react with concentrated nitric acid to form the metal nitrates, nitrogen dioxide and water. Write the balanced equation for the reaction of
- January 2021, AS Unit 2, Q7 (1 mark): −, oxidise dithionate ions, S2O6 2−, according to the equation 7 Iodate(V) ions, IO3 x IO3 − + y S2O6 2− + 4H2O → z SO4 2− + 8H+ + I2 What are the balancing num
- October 2020, AS Unit 1, Q2(b) (1 mark): Which is the ionic half‑equation for a process that takes place during this reaction? (1) A Cu2+ + e– → Cu+ B Cu+ + e– → Cu C Zn → Zn+ + e– D Zn → Zn2+ + 2e–
- October 2020, AS Unit 2, Q6 (1 mark): Dichromate(VI) ions may be reduced in acidic solution. 2–(aq) + x H+(aq) + y e– → 2Cr3+(aq) + z H2O(l) Cr2O7 The coefficients in this half‑equation are x y z A
- June 2019, AS Unit 2, Q19(a)(i) (2 marks): Write half-equations for the oxidation and reduction reactions that take place. State symbols are not required. (2)
- June 2019, AS Unit 2, Q19(a)(ii) (1 mark): Use your answers to (a)(i) to write the overall equation for this redox reaction. State symbols are not required. (1)
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