Transition metals as catalystsEdexcel International A Level Chemistry: Mind map

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