plumiWhy complex ions are coloured: Edexcel International A Level Chemistry questions
Edexcel International A Level Chemistry past-paper questions on 17.1.3 Why complex ions are coloured, 2019–2025, with mark schemes and examiner’s reports where available.
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Open the full PDFYour answerQ16(a)(iii)
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Open the full PDFYour answerQ18(a)(i)
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Open the full PDFYour answerQ21(c)
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All 18 questions on Why complex ions are coloured, as a list
- June 2025 (A), Unit 5, Q5 (1 mark): The aqueous solution of a transition metal ion is colourless. Which is the electronic configuration of this ion? A [Ar] 3d8 B [Ar] 3d10 C [Ar] 3d54s1 D [Ar] 3d1
- June 2025 (A), Unit 5, Q16(a)(iii) (3 marks): Explain why [Mn(H2O)6]2+ ions are coloured. (3)
- January 2025, Unit 5, Q2 (1 mark): An aqueous solution of a transition metal ion absorbs frequencies of light corresponding to green, yellow and red. Which ion is likely to be in the solution? A
- October 2024, Unit 5, Q2 (1 mark): Which ion shows the typical property of transition metals by forming coloured complexes? A Cu+ B Ni2+ C Sc3+ D Zn2+
- October 2024, Unit 5, Q18(a)(i) (3 marks): Explain why the [Fe(H2O)6]2+ complex ion is coloured. (3)
- January 2024, Unit 5, Q17(a)(i) (3 marks): Explain why the three isomers have different colours. (3)
- June 2023, Unit 5, Q10 (1 mark): Which ion is not blue? A VO2+ B [Co(H2O)6]2+ C [Cr(H2O)6]2+ D [Cu(H2O)6]2+ Use this space for any rough working. Anything you write in this space will gain no c
- 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, Q3 (1 mark): Which complex ion is colourless? A [Al(H2O)6]3+ B [Cu(H2O)6]2+ C [Fe(H2O)6]3+ D [Ni(H2O)6]2+
- June 2022, Unit 5, Q15(c)(ii) (1 mark): The intense colour of this complex is due to the transfer of electrons from the ligand to the chromium(VI) ion. Suggest a possible reason why the colour is not
- January 2022, Unit 5, Q10(a)(ii) (2 marks): Explain why [Ag(NH3)2]+ is colourless. (2)
- October 2021, Unit 5, Q20(c)(vi) (6 marks): The student’s teacher said, 2+ ions are colourless in aqueous solution, the titration can “As TiCl3 is blue and TiO be carried out without an alizarin indicator
- June 2021, Unit 5, Q5 (1 mark): Diamminecopper(I) ions are not coloured because A the d orbitals in copper(I) cannot be split B the energy difference between the split d orbitals is outside t
- June 2021, Unit 5, Q21(c) (3 marks): Invertebrates use a copper complex, haemocyanin, to transport oxygen. Blue oxyhaemocyanin gives invertebrate blood its characteristic colour. Explain why oxyhae
- June 2021, Unit 5, Q21(d)(i) (4 marks): The presence of iron in sodium carbonate can affect its properties; the higher the quality of the sodium carbonate, the lower the proportion of iron. The propor
- January 2021, Unit 5, Q19(b)(ii) (3 marks): Explain why T is coloured while V is colourless. A detailed explanation of the fact that T is coloured is not required. (3)
- October 2020, Unit 5, Q25(d) (2 marks): The Lanthanides The lanthanides form a series in the Periodic Table comprising the elements from lanthanum, La (Z = 57) to lutetium, Lu (Z = 71). They have impo
- October 2020, Unit 6, Q1(d) (1 mark): Give a possible reason why compound A is green. (1)
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