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AQA · GCSE · Chemistry · Higher

Catalysed reaction profile construction

Q02.4 2 marks

Nitric acid is produced by reacting ammonia with oxygen. The word equation for the production of nitric acid is:

text{ammonia} + text{oxygen} rightarrow text{water} + text{nitric acid}

Platinum is a catalyst in this reaction. Figure 2 represents the reaction profile of the catalysed reaction between ammonia and oxygen.

Figure 2
Figure 2

Figure 2

Enlarged question image

Figure 2

Complete the reaction profile for the catalysed reaction in Figure 2.

  • label the activation energy
  • label the reactants and products, using the names of the reactants and products

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Marking points

  1. 1 Shows the labelled activation-energy arrow from the reactant energy level to the peak.
  2. 2 Correctly labels both sides: ammonia and oxygen as reactants; nitric acid and water as products (names or accepted formulae).

Why this answer loses marks

The peak is labelled as the activation energy and the two energy levels are left unnamed.

Activation energy must be shown as a vertical interval, and the reactant and product levels also need the substance labels from the equation.