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Edexcel IAL Chemistry 9.6 Catalysed and uncatalysed reaction profiles

Place both routes on identical endpoints, draw the catalysed peak lower, measure each Eₐ upward from reactants and show ΔH between endpoint levels with direction.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • Draw both pathways on common endpoints with the catalysed peak below the uncatalysed peak.
  • Label each Eₐ from the reactant level to its peak and ΔH between endpoint levels.
  • Include a distinct intermediate energy level when the catalysed mechanism requires one.

9.6—Draw the reaction profiles for uncatalysed and catalysed reactions question 1

[Maximum number: 3]

Ammonium nitrate, NH4NO3\mathrm{NH}_{4} \mathrm{NO}_{3}, is used in the manufacture of fertilisers and explosives. It is produced on a large scale using only methane, water and air.
The process has four stages.

The reaction in Stage 2 has an activation energy, Ecat =+70 kJ mol−1E_{\text {cat }}=+70 \mathrm{~kJ} \mathrm{~mol}^{-1}.

The uncatalysed reaction between N2\mathrm{N}_{2} and H2\mathrm{H}_{2} has an activation energy, Ea=+290 kJ mol−1E_{\mathrm{a}}=+290 \mathrm{~kJ} \mathrm{~mol}^{-1}.

Complete the profile for the catalysed and uncatalysed reactions.

Label the activation energies and the enthalpy change of reaction, ΔH\Delta H.
Your diagram must match the scale shown for the production of NH3\mathrm{NH}_{3}.

Figure for Question 9.6—Draw the reaction profiles for uncatalysed and catalysed reactions question 1 — Edexcel A-Level Chemistry AS
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