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Transition metals as catalystsEdexcel International A Level Chemistry: Flashcards

What these 14 flashcards ask

  • What is a heterogeneous catalyst?
  • What is a homogeneous catalyst?
  • Why are transition metals good catalysts?
  • Which catalyst is used in the Contact process?
  • Write the first step of V₂O₅ catalysis in the Contact process.
  • Write the second step of V₂O₅ catalysis.
  • What is the equation for the reaction in a catalytic converter?
  • Describe the three stages of heterogeneous catalysis in a catalytic converter.
  • Why is the catalyst in a converter spread on a honeycomb?
  • Why is the reaction of I⁻ with S₂O₈²⁻ slow?
  • Write the two steps of Fe²⁺ catalysis of I⁻ with S₂O₈²⁻.
  • What is autocatalysis?
  • Which ion autocatalyses the reaction of MnO₄⁻ with C₂O₄²⁻?
  • Write the steps showing Mn²⁺ catalysis.

Exam questions on Transition metals as catalysts

  1. In the Contact process, sulfur dioxide and oxygen are passed over a solid vanadium(V) oxide catalyst at about 450 °C to make sulfur trioxide: SO₂(g) + ½O₂(g) ⇌ SO₃(g).
    Write two equations to show how vanadium(V) oxide acts as a catalyst, and state the oxidation number change of vanadium in each.2 marks
  2. A car exhaust system contains a catalytic converter, a ceramic honeycomb coated with a thin layer of platinum and rhodium. It converts carbon monoxide and nitrogen monoxide in the exhaust gases into carbon dioxide and nitrogen.
    Write an equation for the reaction of carbon monoxide with nitrogen monoxide in the converter, and explain why it is important that the products leave the surface.2 marks
  3. The reaction between iodide ions and peroxodisulfate ions, S₂O₈²⁻ + 2I⁻ → 2SO₄²⁻ + I₂, is very slow at room temperature. When a few drops of aqueous iron(II) sulfate are added, the reaction becomes much faster.
    Write two equations to show how Fe²⁺ ions catalyse this reaction and state why iron is suited to this role.3 marks
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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).