Transition metal redox and ligand exchange: Edexcel International A Level Chemistry questions

Every Edexcel International A Level Chemistry exam question on Transition metal redox and ligand exchange (specification points 17.18–17.25), 2019–2025, with its mark scheme and examiner’s report.

All 110 questions on Transition metal redox and ligand exchange, as a list

June 2025, Unit 5, Q5 (1 mark): 2+ ions? 5 What is the colour of an aqueous solution of V A blue B green C purple D yellow Use this space for any rough working. Anything you write in this spac
June 2025, Unit 5, Q15(c) (2 marks): In human cells, the two chloride ions are replaced by water molecules in a ligand exchange reaction as shown. 2+ + 2Cl − PtCl2(NH3)2 + 2H2O  [Pt(NH3)2(H2O)2 ]
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)
June 2025, Unit 5, Q19 (6 marks): *19 A solution containing tetrachlorocuprate(II) ions, [CuCl4] 2−, is treated with dilute aqueous ammonia. The ammonia solution is added gradually. The followin
June 2025, Unit 6, Q1(a)(ii) (1 mark): Add excess aqueous A pale brown precipitate sodium hydroxide to a forms, which darkens of the cation solution of A and leave to in A is on standing. stand in ai
June 2025, Unit 6, Q1(b)(i) (3 marks): Write ionic equations to account for the following observations. State symbols are not required. (3) Formation of green precipitate in Test 1 Formation of gas t
June 2025, Unit 6, Q1(b)(ii) (1 mark): The brown precipitate from Test 1 was dissolved in sulfuric acid. A yellow-brown solution formed. Give the formula of the complex ion present in the yellow-brow
June 2025, Unit 6, Q1(b)(iii) (1 mark): State the formula of salt B. (1)
June 2025 (A), Unit 5, Q16(b) (3 marks): Explain why aqueous solutions of some complex ions are acidic by comparing the data in the table. (3) pH of a solution of Complex ion formula concentration of 1
June 2025 (A), Unit 5, Q16(c)(i) (2 marks): State the changes that would be observed in Step 1. (2)
January 2025, Unit 5, Q4 (1 mark): What is the colour of the VO2+ ion in aqueous solution? A blue B green C violet D yellow
January 2025, Unit 5, Q20(a)(iii) (2 marks): Give the formula of the species responsible for the purple colour formed in Reaction 3, naming the type of reaction that occurs. (2)
January 2025, Unit 5, Q20(a)(iv) (2 marks): State whether or not the reaction in Reaction 4 is a redox reaction. Justify your answer using oxidation numbers. (2)
January 2025, Unit 5, Q21(c) (2 marks): Suggest why iron(II) sulfate is acidic when dissolved in water. (2)
January 2025, Unit 6, Q1(a)(i) (1 mark): Give the colour of the solution formed. (1)
January 2025, Unit 6, Q1(a)(ii) (1 mark): State the formula of the complex ion. (1)
January 2025, Unit 6, Q1(b)(i) (1 mark): State the formula of Q. (1)
January 2025, Unit 6, Q1(c) (2 marks): A sample of solid Q was added to manganese(IV) oxide and excess sulfuric acid. A redox reaction occurred forming a mixture containing dichromate(VI) ions, Cr2O
January 2025, Unit 6, Q1(d)(i) (1 mark): Give the formula of the complex ion that forms the green colour. (1)
January 2025, Unit 6, Q1(d)(ii) (1 mark): Name the type of reaction that has taken place. (1)
October 2024, Unit 5, Q5 (1 mark): Chromium(III) hydroxide, Cr(OH)3(H2O)3 , is amphoteric. This means that chromium(III) hydroxide dissolves in A water B strong acid only C strong alkali only D s
October 2024, Unit 6, Q1(a)(iii) (2 marks): Give the formulae of the three ions present in Q and hence the formula of compound Q. (2) Ions in Q Formula of Q
June 2024, Unit 5, Q1 (1 mark): What colour is vanadium(III) in aqueous solution? A blue B green C purple D yellow
June 2024, Unit 5, Q16(a) (2 marks): Complete the equation for the reaction of a laboratory reagent with aqueous Fe3+ ions to produce a precipitate. Include state symbols in your answer. (2) [Fe(H2
June 2024, Unit 6, Q2(a)(i) (2 marks): Complete the table giving the observations you would see. (2) Observation on adding a few Observation on adding an drops of sodium hydroxide excess of sodium hy
June 2024, Unit 6, Q2(a)(ii) (1 mark): State what you can deduce about the nature of chromium(III) hydroxide from the results of Experiment 1. (1)
June 2024, Unit 6, Q2(b) (2 marks): Experiment 2 5 cm3 of hydrogen peroxide solution is added to the final mixture formed in (a) (i) and heated gently. 2–, is produced. A yellow solution containin
June 2024, Unit 6, Q2(c) (1 mark): Experiment 3 Dilute sulfuric acid is added to the yellow solution formed in Experiment 2. The solution turns orange. Complete and balance the equation for this
January 2024, Unit 5, Q5(b) (1 mark): Which rows show the substances with their correct oxidation states? (1) Cu(0) Cu(I) Cu(II) A S U P B S R Q C T S P D T U Q
January 2024, Unit 5, Q5(c) (1 mark): Aqueous solution X contains (1) A H2SO4 B KI C NaOH D NH3
January 2024, Unit 5, Q17(b)(i) (1 mark): Write the balanced equation for Step 1. State symbo
January 2024, Unit 6, Q1(a)(i) (1 mark): Dilute aqueous A pale blue precipitate The cation in A is (1) ammonia was added formed which drop‑by‑drop to 4 cm3 dissolved to give a of A until there was no d
January 2024, Unit 6, Q1(a)(ii) (2 marks): Dilute aqueous A white precipitate The formula of the (2) ammonia was added formed with the first white precipitate is drop‑by‑drop to 4 cm3 few drops of B unti
January 2024, Unit 6, Q1(a)(iii) (2 marks): Dilute aqueous (2) sodium hydroxide was added drop‑by‑drop to 4 cm3 of C until there was no further change
January 2024, Unit 6, Q1(a)(iv) (1 mark): Dilute aqueous An off‑white precipitate sodium hydroxide was formed which did not added drop‑by‑drop to dissolve in excess but 4 cm3 of D until there darkened w
January 2024, Unit 6, Q1(a)(v) (1 mark): Name the type of reaction which results in the darkening of the off‑white precipitate in (a)(iv). (1)
January 2024, Unit 6, Q1(c) (1 mark): The student tested for the anion in C by adding acidified barium nitrate solution and observed a white precipitate. Give the formula of the compound in solution
January 2024, Unit 6, Q3(a)(ii) (1 mark): The cotton wool helps to prevent the reoxidation of the vanadium and to allow the escape of hydrogen gas. State why hydrogen gas was produced. You may include a
January 2024, Unit 6, Q3(a)(iii) (1 mark): Give a possible reason why the flask was heated. (1)
January 2024, Unit 6, Q3(a)(iv) (3 marks): The student concluded that zinc had reduced the vanadium(V) to the vanadium(II) oxidation state. Explain the sequence of colours that the student would have see
October 2023, Unit 5, Q4 (1 mark): Aqueous sodium hydroxide and aqueous ammonia are added, until they are in excess, to separate portions of a pale green aqueous solution E. Test Observations Gre
October 2023, Unit 5, Q5 (1 mark): A small amount of aqueous ammonia is added to an aqueous solution containing zinc ions. A white precipitate forms. Which is the equation for this reaction? A [Z
June 2023, Unit 5, Q11 (1 mark): Which equation shows a redox reaction in which the solution turns yellow? A Fe + 2HCl → FeCl2 + H2 B VO3 – + 2H+ → VO2 + + H2O C Cr2O7 2– + 2OH– → 2CrO4 2– + H2
June 2023, Unit 5, Q12 (1 mark): Aqueous ammonia is added in excess to an aqueous solution of Cu2+. What is the equation for the overall reaction? A [Cu(H2O)6]2+ + 2NH3 → [Cu(H2O)4(OH)2] + 2NH4
June 2023, Unit 5, Q13 (1 mark): Which equation shows the formation of a precipitate? A [Zn(OH)4]2– + 2H3O+ → [Zn(H2O)4(OH)2] B [Zn(H2O)6]2+ + 4OH– → [Zn(OH)4]2– + 6H2O C [Cr(H2O)3(OH)3] + 3H3O
June 2023, Unit 6, Q1(a)(i) (1 mark): A few drops of aqueous Chromium(III) ions (1) sodium hydroxide were may be present in P added to 5 cm3 of P
June 2023, Unit 6, Q1(a)(ii) (1 mark): More sodium hydroxide Chromium(III) ions (1) solution was added are confirmed to be to the mixture from present in P (a)‌(i) until there was no further change
June 2023, Unit 6, Q1(c)(i) (2 marks): The addition of dilute aqueous ammonia to a sample of solution Q produced a green precipitate which changed colour on standing. Explain why the colour change le
June 2023, Unit 6, Q1(d) (1 mark): Identify, by name or formula, a metal cation, other than chromium(III) and iron(II), which could give a green colour in an aqueous solution. (1)
January 2023, Unit 5, Q4 (1 mark): Which metal hydroxide precipitate is soluble in both excess aqueous ammonia and excess aqueous sodium hydroxide? A Cu(OH)2 B Fe(OH)2 C Ni(OH)2 D Zn(OH)2
January 2023, Unit 5, Q6 (1 mark): The diagram shows how the relative colour intensity of an aqueous solution containing 0.001 mol of chromium(III) ions varies with increasing amounts of cyanide
January 2023, Unit 5, Q18(e) (6 marks): Vanadium(V) ions, VO2 oxidation states. Compare and contrast the use of iron and tin in this reduction process. Include equations and Ecell values for any react
January 2023, Unit 5, Q20(c) (1 mark): Potassium manganate(VI), K2MnO4 , is a green solid. In acidic solution, the manganate(VI) ions disproportionate to form manganate(VII) ions and manganese(IV) ox
January 2023, Unit 6, Q1(a) (2 marks): Give the formulae of three cations which could be responsible for the green colour. (2)
January 2023, Unit 6, Q1(b)(i) (1 mark): Give the formula of the green precipitate from solution A. (1)
January 2023, Unit 6, Q1(b)(ii) (1 mark): Give the formula of the species responsible for the dark green colour in solution C. (1)
January 2023, Unit 6, Q1(c)(i) (1 mark): State the type of reaction involved when the dark green solution turned yellow. (1)
January 2023, Unit 6, Q1(c)(ii) (1 mark): Identify, by name or formula, the ion responsible for the final orange colour of the solution. (1)
October 2022, Unit 5, Q19(b)(i) (4 marks): Justify the use of sodium thiosulfate for this reaction by writing the relevant equations and calculating their Ecell values. Use the standard electrode potenti
October 2022, Unit 5, Q19(b)(ii) (2 marks): Explain why nickel, Ni, is not a suitable reagent to convert VO2+ into V3+, with no other vanadium species being formed. (2)
October 2022, Unit 5, Q22(b)(i) (1 mark): Name the type of reaction that occurs when concentrated hydrochloric acid is added to aqueous cobalt(II) sulfate. (1)
October 2022, Unit 5, Q22(b)(ii) (2 marks): Write an ionic equation for the reaction that occurs when concentrated hydrochloric acid is added to aqueous cobalt(II) sulfate. State symbols are not required.
October 2022, Unit 5, Q22(b)(iii) (2 marks): Explain why the shape of the complex ion changes when concentrated hydrochloric acid is added. (2)
October 2022, Unit 6, Q1(a)(iii) (1 mark): Add concentrated The formula of the complex ion formed is [CoCl4]2– hydrochloric acid
October 2022, Unit 6, Q1(a)(iv) (1 mark): Add a small A blue precipitate forms The type of reaction amount of that takes place with the dilute aqueous complex ion during this ammonia precipitation is
October 2022, Unit 6, Q1(a)(v) (3 marks): dilute aqueous ion formed is ammonia to the precipitate formed in (iv), until no further change is seen
June 2022, Unit 5, Q3 (1 mark): Excess aqueous sodium thiosulfate is added to an aqueous solution of ammonium vanadate(V). What colour is the mixture when the reaction is complete? Refer to pa
June 2022, Unit 5, Q5 (1 mark): Which reagent, when added to aqueous sodium dichromate(VI), Na2Cr2O7(aq), causes a shift in equilibrium resulting in the formation of a yellow solution? A NaOH(
June 2022, Unit 5, Q13 (6 marks): *13 Compare and contrast the reactions in aqueous solution of nickel(II) sulfate with sodium hydroxide and with ammonia. For each reaction include • what would
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
June 2022, Unit 5, Q17(b) (4 marks): After the copper(I) thiocyanate is precipitated, Zn2+ ions remain in solution. A student suggested that these Zn2+ ions can be precipitated by adding a large ex
June 2022, Unit 6, Q1(a)(i) (2 marks): Identify, by name or formula, the salt in A. (2)
January 2022, Unit 5, Q14 (6 marks): *14 Describe the reactions of separate samples of aqueous cobalt(II) sulfate with aqueous sodium hydroxide, excess aqueous ammonia and concentrated hydrochloric
January 2022, Unit 6, Q1(a) (1 mark): Give the formula of a complex ion of chromium present in solution A. (1)
January 2022, Unit 6, Q1(b) (1 mark): Give the formula of precipitate B. (1)
January 2022, Unit 6, Q1(c) (1 mark): Identify reagent C, by name or formula. (1)
January 2022, Unit 6, Q1(d) (1 mark): Suggest the identity, by name or formula, of precipitate D. (1)
January 2022, Unit 6, Q1(e) (1 mark): State the colour of solution E. (1)
January 2022, Unit 6, Q1(f) (1 mark): State the colour of solution F. (1)
October 2021, Unit 5, Q6 (1 mark): Aqueous ammonia is added drop by drop to a solution of cobalt(II) chloride, CoCl2(aq), until in excess. What would be the sequence of observations? A blue solut
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, Q18(f) (2 marks): Complete the table, using  as appropriate, to identify the type of each reaction. (2) Neutralisation Ligand exchange Redox Reaction 2 Reaction 3
October 2021, Unit 6, Q1(a)(i) (1 mark): Test 1 A few drops of aqueous sodium hydroxide were added to a sample of the copper(II) sulfate solution. State what you would see. (1)
October 2021, Unit 6, Q1(a)(ii) (2 marks): Test 2 A few drops of concentrated hydrochloric acid were added to another sample of the copper(II) sulfate solution. More of the concentrated hydrochloric acid
June 2021, Unit 5, Q7 (1 mark): Aqueous sodium hydroxide was added to aqueous iron(II) sulfate and the mixture allowed to stand. What would be observed? Observations Immediately after adding A
June 2021, Unit 5, Q8 (1 mark): When aqueous ammonia is added to an aqueous solution of zinc sulfate, a white precipitate forms which dissolves in excess ammonia to give a colourless solution.
June 2021, Unit 6, Q1(a)(i) (1 mark): When excess dilute sulfuric acid is added to an aqueous solution of NH4VO3 , − ion is converted into the VO2 + ion. the VO3 Write the ionic equation for the con
June 2021, Unit 6, Q1(a)(ii) (1 mark): State the colour of an acidified solution of ammonium vanadate(V). (1)
June 2021, Unit 6, Q1(a)(iii) (2 marks): A student added zinc metal to an acidified solution of ammonium vanadate(V). The zinc reduced the vanadium in a series of reactions. The student suggested that
June 2021, Unit 6, Q1(a)(iv) (2 marks): When the mixture obtained at the end of the sequence in (a)(iii) is filtered, the filtrate changes colour from violet to green on standing. No further changes
June 2021, Unit 6, Q1(b)(i) (2 marks): Suggest the formulae of two complex ions present in solution T. (2)
June 2021, Unit 6, Q1(b)(ii) (1 mark): State how the colour of solution T would change on the addition of excess concentrated hydrochloric acid. (1)
June 2021, Unit 6, Q1(b)(iii) (1 mark): Describe what would be observed on the addition of aqueous sodium hydroxide to solution T. (1)
June 2021, Unit 6, Q2(b) (1 mark): Give the colour of the solution at the end of Step 2. (1)
January 2021, Unit 5, Q19(a) (7 marks): Identify, by name (including the oxidation state) or formula, the species in the sequence that contain copper. (7) P Q R S T V W
January 2021, Unit 5, Q19(b)(iii) (2 marks): Suggest an explanation for the change of V into T on shaking. (2)
January 2021, Unit 5, Q19(c)(i) (1 mark): Write the ionic equation for this disproportionation reaction. State symbols are not required. (1)
January 2021, Unit 5, Q21(c) (1 mark): Write the ionic equation for the reaction of the aqueous solution of E with dilute sulfuric acid. State symbols are not required. (1)
January 2021, Unit 6, Q1(b)(vi) (2 marks): A concentrated solution of ammonia is added to B. Initially a pale blue precipitate forms. When more ammonia is added, the precipitate dissolves forming a dark
January 2021, Unit 6, Q1(b)(vii) (2 marks): A solution of the sodium salt of EDTA, Na4EDTA, is added to a sample of solution F. The solution turns pale blue. Write an equation for the reaction. State symb
October 2020, Unit 5, Q24(a)(i) (2 marks): Complete the equation for Reaction 1. State symbols are not required. (2) [Fe(H2O)6]3+ + ……………….. NH3 →
October 2020, Unit 5, Q24(a)(ii) (1 mark): State the type of reaction occurring in Reaction 2. (1)
October 2020, Unit 5, Q24(b)(i) (2 marks): Complete the table to show the colours of the ions that each of these oxidation states has in aqueous solution. (2) Colour of the ions in Oxidation state of van
October 2020, Unit 5, Q24(b)(ii) (1 mark): Two vanadium species exist in equilibrium in an aqueous solution. −(aq) + H2O(l) ⇌ VO2 VO3 +(aq) + 2OH−(aq) Deduce whether or not this is a redox reaction. Just
October 2020, Unit 5, Q24(b)(iii) (5 marks): Predict the oxidising agent that could convert vanadium(II) ions to vanadium(III) ions and then vanadium(IV) ions, but not to vanadium(V) ions, under standard c
October 2020, Unit 6, Q1(a)(i) (2 marks): B dissolved in excess ammonia to form a deep blue solution containing a complex ion D. Identify, by name or formula, B and D. (2) Precipitate B Complex ion D
October 2020, Unit 6, Q1(a)(ii) (1 mark): When another portion of B was heated gently, the solid turned black. Suggest the name or formula of the black solid. (1)
October 2020, Unit 6, Q1(a)(iii) (1 mark): Excess concentrated hydrochloric acid was added to a further portion of B and the mixture warmed. The precipitate dissolved to form a different yellow solution
October 2020, Unit 6, Q1(b)(i) (3 marks): Identify, by name or formula, the ions responsible for the colours observed. (3) Observation Ions yellow colour of solution C orange colour on adding dilute sul
October 2020, Unit 6, Q1(c) (1 mark): Give the name or formula of compound A. (1)

Questions, mark schemes and examiner’s reports are © Pearson Edexcel, from their published past papers. Plumi isn’t affiliated with any exam board. Want whole papers? Every Edexcel International A Level Chemistry paper.

Rather write your answers by hand on iPad? Plumi marks them against the same mark schemes.

4,117 questions