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3.2 Energetics

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Question 6

Nitrogen reacts with hydrogen to make ammonia:

N2+3H2→2NH3 \text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3 N2​+3H2​→2NH3​

Breaking all the bonds in the reactants takes in 2253 kJ/mol. Making all the bonds in the products releases 2346 kJ/mol.

Which statement about this reaction is correct?

[1]
A

The energy change is +93 kJ/mol+93\,\mathrm{kJ/mol}+93kJ/mol, so the temperature of the surroundings rises.

B

The energy change is −93 kJ/mol-93\,\mathrm{kJ/mol}−93kJ/mol, so the temperature of the surroundings falls.

C

The energy change is −93 kJ/mol-93\,\mathrm{kJ/mol}−93kJ/mol, so the temperature of the surroundings rises.

D

The energy change is +93 kJ/mol+93\,\mathrm{kJ/mol}+93kJ/mol, so the temperature of the surroundings falls.

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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