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CAIE A Level Chemistry 9701

Chemistry of transition elements questions

Exam-style questions on Chemistry of transition elements, ordered from foundation to challenge. Pick one, write your answer the way you would in the exam, and it comes back marked against the mark scheme, point by point.

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Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.

  1. Compare5 marksStandardCis-platin, [Pt(NH3)2Cl2], is a square planar complex used as a cancer drug. Another complex, ce[Co(NH3)4(H2O)2]^2+, is octahedral. Compare the types of stereoisomerism shown by these two complexes, and state whether…
  2. Compare5 marksStandardAn aqueous solution of cobalt(II) chloride contains the complex ce[Co(H2O)6]^2+ and is pink. When concentrated hydrochloric acid is added, the colour changes to blue as the tetrahedral complex ce[CoCl4]^2- is formed…
  3. Suggest4 marksStandardA complex has the formula [Ni(H2NCH2CH2NH2)2(H2O)2]^2+, where H2NCH2CH2NH2 is the bidentate ligand ethane-1,2-diamine. Suggest the types of stereoisomerism this complex can show, and state whether any of these isomers…
  4. Explain4 marksStandardA complex is formed when nickel(II) chloride reacts with an excess of ethane-1,2-diamine, H2NCH2CH2NH2, a bidentate ligand. The complex ion has the formula [Ni(H2NCH2CH2NH2)3]^2+. Explain why this complex ion can exist…
  5. Compare5 marksStandardTwo copper(II) complexes are formed from the hexaaquacopper(II) ion in aqueous solution. Complex A: ce[Cu(H2O)6]^2+ + 4NH3 - [Cu(NH3)4(H2O)2]^2+ + 4H2O Complex B: ce[Cu(H2O)6]^2+ + 2en - [Cu(en)2]^2+ + 6H2O (where en =…
  6. Describe5 marksStandardAn octahedral cobalt(III) complex has the formula [Co(NH3)4Cl2]+. The two chloride ligands can be arranged either on adjacent positions or on opposite positions. (a) Name the type of stereoisomerism shown by this…
  7. Explain4 marksStandardA cobalt(III) complex has the formula ce[Co(en)2(H2O)2]^3+, where en is ethylenediamine (H2NCH2CH2NH2), a bidentate ligand. Explain the types of stereoisomerism that this complex can exhibit. For each type, state which…
  8. Explain4 marksStandardAn aqueous solution of copper(II) sulfate is pale blue. When concentrated hydrochloric acid is added, the solution turns yellow-green. Explain, in terms of d orbital splitting and electron transitions, why the aqueous…
  9. Compare5 marksStandardTwo nickel(II) complexes are studied. Complex A is [Ni(H2NCH2CH2NH2)2(H2O)2]^2+ and complex B is [Ni(H2NCH2CH2NH2)3]^2+. Compare the types of stereoisomerism shown by these complexes. In your answer, refer to the…
  10. Explain4 marksStandardA student adds aqueous ammonia, in small portions, to an aqueous solution of copper(II) sulfate. Explain, in terms of ligand exchange, what the student observes and why the changes occur.
  11. Explain4 marksStandardAqueous cobalt(II) ions exist as the pink complex ce[Co(H2O)6]^2+. When concentrated hydrochloric acid is added, the solution turns blue as the complex ce[CoCl4]^2- forms. Explain this colour change in terms of…
  12. Explain4 marksStandardIron is used as a catalyst in the Haber process for the manufacture of ammonia. Using the properties of transition elements, explain why iron is able to act as a catalyst in this reaction.
  13. Explain4 marksStandardVanadium is a d-block element that can act as a catalyst in some reactions. Using vanadium as an example, explain why transition elements can behave as catalysts.
  14. Describe5 marksStandardThe blue colour of an aqueous solution of copper(II) sulfate is due to the complex ion [Cu(H2O)6]^2+. Describe the structure and bonding of this complex ion. Define the terms ligand and complex in your answer.
  15. Describe5 marksStandardWhen an excess of concentrated ammonia solution is added to an aqueous solution containing the hexaaquacopper(II) ion, [Cu(H2O)6]^2+, a ligand exchange reaction occurs and a deep blue solution is formed. Describe the…
  16. Suggest4 marksStandardAn aqueous solution of copper(II) sulfate is pale blue. When concentrated hydrochloric acid is added, the solution turns green. Suggest why the colour changes when the ligand is changed from water to chloride ions.
  17. Explain4 marksStandardThe stability constant, mathrmKstab, for the formation of ce[Cu(NH3)4]^2+ is 1.1 imes 10^12 and for ce[Cu(H2O)6]^2+ is 1.0 imes 10^8. Explain why ce[Cu(NH3)4]^2+ is less likely to undergo ligand exchange with water…
  18. Describe5 marksStandardAn aqueous solution of cobalt(II) chloride is pink. When concentrated hydrochloric acid is added, the solution turns blue. The pink colour is due to the octahedral complex [Co(H2O)6]^2+ and the blue colour is due to…
  19. Explain4 marksStandardWhen silver(I) chloride, AgCl, is treated with an excess of aqueous ammonia, the precipitate dissolves. Explain, in terms of ligand exchange, why the precipitate dissolves and why the ammonia is described as a ligand…
  20. Describe5 marksStandardA student adds aqueous ammonia to a suspension of copper(II) hydroxide, Cu(OH)2. The pale blue solid dissolves to give a deep blue solution containing the complex ion ce[Cu(NH3)4(H2O)2]^2+. Describe and explain, with…
  21. Compare5 marksStandardA student dissolves cobalt(II) chloride in distilled water and observes a pink solution. When concentrated hydrochloric acid is added, the solution turns blue. The student is told that the blue colour is due to the…
  22. Compare5 marksStandardThe chromium(III) ion, ceCr^3+, forms a violet complex ion in aqueous solution. The calcium ion, ceCa^2+, forms a colourless solution. Compare the chromium(III) ion with the calcium ion in terms of the definition of a…
  23. Suggest4 marksStandardAqueous copper(II) ions exist as the complex ion ce[Cu(H2O)6]^2+. Suggest why copper(II) is able to form this complex ion, and explain why this complex ion is coloured.
  24. Explain4 marksStandardWhen solid CoCl2 is dissolved in water, the solution contains the pink octahedral complex ion [Co(H2O)6]^2+. Adding concentrated hydrochloric acid changes the solution to a deep blue colour as the ion [CoCl4]^2- forms…
  25. Describe5 marksStandardA student prepares a solution containing the complex ion ce[Fe(C2O4)3]^3-, formed when ethanedioate ions, ceC2O4^2-, coordinate to ceFe^3+ ions. Describe this complex ion in terms of: the type of ligand and the type of…
  26. Compare5 marksStandardCopper(II) sulfate is dissolved in water, giving a pale blue solution. Concentrated hydrochloric acid is added, and the solution turns yellow-green. In a separate experiment, cobalt(II) chloride is dissolved in water…
  27. Suggest4 marksStandardA student adds an excess of aqueous ceEDTA^4- to an aqueous solution containing ce[CuCl4]^2- ions. Suggest why the ce[CuCl4]^2- complex is converted into a complex containing ceEDTA^4- as the only ligand. In your…
  28. Compare6 marksChallengeManganese forms stable ions in oxidation states +2, +3, +4, +6 and +7. The 3d and 4s sub-shells in manganese atoms have similar energies. Compare the behaviour of manganese with that of a typical s-block element such…
  29. Describe5 marksChallengeIn an aqueous solution containing an excess of ethanedioate ions, ceFe^3+ ions react to form a complex ion in which each iron(III) ion is surrounded by three ethanedioate ligands. The ethanedioate ion, ceC2O4^2-, is a…
  30. Explain7 marksChallengeA square planar complex has the formula [Pt(NH3)2Cl2]. One isomer of this complex is polar, while the other isomer is non-polar. Explain, in terms of the positions of the ligands, why one isomer is polar and the other…
  31. Explain7 marksChallengeSilver(I) ions in aqueous solution form the complex ion [Ag(H2O)2]+, which is linear. When an excess of aqueous sodium cyanide is added, the complex [Ag(CN)2]- forms. Explain, in terms of ligand exchange, why the…
  32. Describe7 marksChallengeA student adds concentrated hydrochloric acid to an aqueous solution of cobalt(II) chloride. The solution changes from pink to blue. Describe, in terms of d orbital splitting, why this colour change occurs.
  33. Describe5 marksChallengeIn the Contact process, V2O5 is used as a catalyst for the oxidation of SO2 to SO3. (a) State the two features of a transition element that allow it to behave as a catalyst. (b) The vanadium in V2O5 is in oxidation…
  34. Suggest5 marksChallengeA student adds an excess of concentrated ammonia solution to an aqueous solution containing the hexaaquacopper(II) ion, [Cu(H2O)6]^2+. A pale blue precipitate forms first and then dissolves to give a deep blue…
  35. Suggest5 marksChallengeA student dissolves anhydrous cobalt(II) chloride in water, producing a pink solution. On adding concentrated hydrochloric acid, the solution turns blue. The blue species is the tetrahedral complex ion [CoCl4]^2-…
  36. Explain7 marksChallengeAn aqueous solution of cobalt(II) chloride is pink. When concentrated hydrochloric acid is added, the solution turns blue. The blue species is the tetrahedral complex ion [CoCl4]^2-. Explain, in terms of the splitting…
  37. Describe7 marksChallengeThe stability constant, Kstab, is an equilibrium constant for the formation of a complex ion. Two cobalt(III) complexes are: ce[Co(NH3)6]^3+ has Kstab = 4.5 × 10^33 ce[Co(H2O)6]^3+ has Kstab = 1.0 × 10^18 (a) Define…
  38. Suggest5 marksChallengeZinc forms the ion ceZn^2+ with the electronic configuration [Ar] 3d^10. Suggest why zinc is not classified as a transition element, and explain how the absence of this classification affects its catalytic behaviour…
  39. Compare6 marksChallengeA student prepares two aqueous solutions of copper(II) sulfate. To one solution, an excess of concentrated hydrochloric acid is added; to the other, an excess of concentrated ammonia solution is added. In each case, a…
  40. Describe7 marksChallengeThe anticancer drug cisplatin is the cis isomer of the square planar complex [Pt(NH3)2Cl2]. Its trans isomer is not used as a drug. Describe the stereoisomerism shown by [Pt(NH3)2Cl2], and explain why the trans isomer…
  41. Describe7 marksChallengeA student investigates colour changes of transition metal complexes. A pink aqueous solution of ce[Co(H2O)6]^2+ turns blue on addition of concentrated hydrochloric acid, forming ce[CoCl4]^2-. The same pink solution…
  42. Compare6 marksChallengeAn aqueous solution containing the complex ion ce[Ni(H2O)6]^2+ is pale green. When concentrated hydrochloric acid is added, the solution turns yellow and a new complex ion forms. In a separate experiment, an aqueous…
  43. Explain7 marksChallengeIn the Haber process, N2(g) + 3H2(g) ⇌ 2NH3(g), a porous iron catalyst is used. Explain, in terms of the electronic structure and bonding of transition elements, why iron is able to act as a catalyst in this reaction.