Transition Metals & Complexes (Edexcel International A Level Chemistry)

Exam Questions

55 mins15 questions
11 mark

What is the electronic configuration of a chromium atom?

q3-paper-5-june-2021-edexcel-ial-chemistry

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    21 mark

    A ligand must be an

    • electron-pair donor

    • electron-pair donor and negatively charged

    • electron-pair acceptor

    • electron-pair acceptor and negatively charged

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    31 mark

    Nickel is classified as a transition metal. This is because nickel

    • is a d block element

    • has partially filled d orbitals

    • forms stable ions with partially filled d orbitals

    • forms stable compounds in which it has different oxidation states

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    41 mark

    Cobalt chloride is used as a test for the presence of water.

    This test depends on the fact that

    • anhydrous cobalt(II) chloride is blue and hydrated cobalt(II) chloride is pink

    • anhydrous cobalt(II) chloride is pink and hydrated cobalt(II) chloride is blue

    • cobalt(II) chloride is blue and cobalt(III) chloride is pink

    • cobalt(II) chloride is pink and cobalt(III) chloride is blue

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    1a1 mark

    This question is about transition metal complexes.

    a)
    The bonding within the complex [Cu(NH3)4(H2O)2]2+ is
    • covalent, dative covalent and ionic

    • covalent and dative covalent only

    • covalent only

    • dative covalent only

    1b1 mark
    b)
    Which complex is tetrahedral?

    • [Pt(NH3)2Cl2]

    •  [Cu(H2O)4(OH)2]

    • [Cu(NH3)4(H2O)2]2+

    • [CoCl4]2−

    1c1 mark
    c)
    Which complex contains a bidentate ligand?
    • [Co(NH2CH2CH2NHCH2CH2NH2)2]3+

    • [Cu(NH3)4(H2O)2]2+

    • [Ni(NH2CH2CH2NH2)3]2+

    • [Mn(EDTA)]2−

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    21 mark

    In which of the following pairs does the metal have different oxidation numbers?

    • CrO subscript 4 superscript 2 minus end superscript space and space Cr subscript 2 straight O subscript 7 superscript 2 minus end superscript 

    • CrO subscript 4 superscript 2 minus end superscript space and space CrO subscript 3 Cl to the power of minus

    • V2O5 and space VO subscript 4 superscript 3 minus end superscript

    • VO subscript 2 superscript plus and VO2+

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    31 mark

    Which of the following statements best explains carbon monoxide poisoning?

    • carbon monoxide binds irreversibly to haemoglobin

    • carbon monoxide forms stronger dative covalent bonds with haemoglobin than oxygen does

    • the formation of carboxyhaemoglobin leads to a large increase in the entropy of the system

    • carbon monoxide has a triple bond whereas oxygen has a double bond

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    41 mark

    Diamminecopper(I) ions are not coloured because

    • the d orbitals in copper(I) cannot be split

    • the energy difference between the split d orbitals is outside the visible region of the spectrum

    • d—d transitions are not possible because the d orbitals are fully occupied

    • copper(I) complexes are readily oxidised

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    51 mark

    Which of these has the greatest number of unpaired electrons in each of its atoms?

    • chromium

    • iron

    • manganese

    • vanadium

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    61 mark

    Copper(II) ions form a complex with 1,2-diaminoethane (symbol ‘en’) with the formula Cu(en)3 2+.

    What type of ligand is 1,2-diaminoethane, and what is the coordination number of copper(II) in the complex?

        Type of ligand Coordination number
    A bidentate 3
    B bidentate 6
    C tridentate 3
    D tridentate 6

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      71 mark

      Some nickel(II) complex ions are formed by the addition of complexing agents to nickel(II) ions, [Ni(H2O)6]2+, in aqueous solution.

      On formation, which of these leads to the most positive increase in ΔSsystem?

      • [NiCl4]2–

      • [Ni(EDTA)]2–

      • [Ni(C2O4)2 ]2–

      • [Ni(H2NCH2CH2NH2)3]2+

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      8a1 mark

      Platinum forms a complex with the formula Pt(NH3)2Cl2 and chromium forms a complex with the formula CrCl4.

      a)
      What are the shapes of these complexes?
      • both complexes are square planar

      • both complexes are tetrahedral

      • Pt(NH3)2Cl2 is tetrahedral and CrCl4 is square planar

      • Pt(NH3)2Cl2 is square planar and CrCl4 is tetrahedral

      8b1 mark
      b)
      What is the bonding between the ligands and the central atom in these complexes?
      • the bonding in both complexes is ionic

      • the bonding in both complexes is dative covalent

      • the bonding in Pt(NH3)2Cl2 is dative covalent and in CrCl4 is ionic

      • the bonding in Pt(NH3)2Cl2 is ionic and in CrCl4 is dative covalent

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