Lesson 15B.1

15B.1 Vanadium and dichromate redox chemistry Quiz: Pearson Edexcel Chemistry, Unit 15

20 questions

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Lesson 15B.1, Vanadium and dichromate redox chemistry: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 15: Transition Metals, written with Revision Ninja.

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The 20 questions

  1. What colour is the vanadium(V) ion, V(+5), in its compounds?

    • Yellow
    • Green
    • Blue
    • Violet
  2. What colour is vanadium(IV) in its compounds?

    • Green
    • Violet
    • Yellow
    • Blue
  3. Which metal reduces vanadium(V) stepwise down to vanadium(II) in acidic conditions?

    • Copper
    • Zinc
    • Iron
    • Silver
  4. What colour is the chromate(VI) ion, CrO4 2-?

    • Green
    • Yellow
    • Orange
    • Pink
  5. What colour is the dichromate(VI) ion, Cr2O7 2-?

    • Yellow
    • Green
    • Blue
    • Orange
  6. What colour change occurs when yellow chromate(VI) solution is acidified?

    • Orange to yellow
    • Yellow to orange
    • Yellow to green
    • Orange to green
  7. What is the oxidation number of vanadium in the VO2+ ion?

    • +4
    • +3
    • +2
    • +5
  8. What is the oxidation number of chromium in both CrO4 2- and Cr2O7 2-?

    • +6 and +7
    • +3 and +6
    • +6 in both
    • +4 and +6
  9. Which ion is favoured when a chromate-dichromate equilibrium mixture is acidified?

    • Chromium(II)
    • Chromate(VI)
    • Chromium(III)
    • Dichromate(VI)
  10. What is E°cell for the reduction of Cr3+ to Cr2+ by zinc?

    • -1.17 V
    • -0.35 V
    • +0.35 V
    • +1.17 V
  11. Which reagent oxidises Cr3+ ions to chromate(VI) ions in alkaline solution?

    • Zinc metal
    • Potassium manganate(VII)
    • Hydrochloric acid
    • Hydrogen peroxide
  12. What is the oxidation state of vanadium in V2O5?

    • +4
    • +5
    • +3
    • +2
  13. Because its Cr3+/Cr2+ electrode potential is negative (-0.41 V), Cr2+ acts as a strong what?

    • Ligand
    • Oxidising agent
    • Reducing agent
    • Catalyst
  14. With E° = +1.33 V, acidified dichromate(VI) ions act as a strong what?

    • Reducing agent
    • Base
    • Ligand
    • Oxidising agent
  15. In the reaction of dichromate with Fe2+ in acid, how many moles of Fe2+ react with 1 mol of Cr2O7 2-?

    • 1
    • 6
    • 3
    • 2
  16. How many moles of Fe2+ react with 25.0 cm3 of 0.0200 mol dm-3 K2Cr2O7?

    • 1.00 x 10^-3 mol
    • 1.20 x 10^-2 mol
    • 3.00 x 10^-3 mol
    • 5.00 x 10^-4 mol
  17. What property determines each step in the reduction of vanadium ions?

    • Electrode potential
    • Ionic radius
    • Activation energy
    • Hydration enthalpy
  18. Which species forms when acid is added to yellow chromate(VI) solution?

    • Cr2O7 2-
    • CrO4 2-
    • Cr3+
    • Cr2+
  19. Why does reducing dichromate(VI) with zinc produce multiple colour changes?

    • Temperature changes
    • Ligand substitution
    • Multiple oxidation states
    • Gas evolution
  20. What colour change is seen when atmospheric oxygen oxidises V2+ to V3+?

    • Yellow to blue
    • Blue to yellow
    • Green to violet
    • Violet to green

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