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3.2 Energetics

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Question 25

A research team is selecting a reaction for an energy-storage system.

The reaction must:

  • take in at least 40 kJ/mol from the surroundings
  • have an activation energy no greater than 80 kJ/mol.

The table shows data from the reaction profiles of two reactions.

ReactionEnergy of reactants (kJ/mol\mathrm{kJ/mol}kJ/mol)Energy at the top of the peak (kJ/mol\mathrm{kJ/mol}kJ/mol)Energy of products (kJ/mol\mathrm{kJ/mol}kJ/mol)
J3512585
K70145115
a.

Calculate the overall energy change and the activation energy for each reaction.

[4]
b.

Evaluate which reaction should be used in the energy-storage system. Use the information in the table and your calculations.

[2]
Markscheme

3.2 Energetics Questions

  1. GCSE
  2. /Chemistry
  3. /3.2 Energetics

106 exam-style questions on OCR GCSE Chemistry 3.2 Energetics, covering 3.2.1 Exothermic and endothermic reactions and reaction profiles and 3.2.2 Calculating energy change from bond energies. Each one has a worked solution and a mark scheme showing where the marks go.

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