Ammonia can be broken down into nitrogen and hydrogen.
2NH3→N2+3H2 \mathrm{2NH_3 \rightarrow N_2 + 3H_2} 2NH3→N2+3H2Each ammonia molecule contains three N−H\mathrm{N-H}N−H bonds. Each nitrogen molecule contains one N≡N\mathrm{N{\equiv}N}N≡N bond and each hydrogen molecule contains one H−H\mathrm{H-H}H−H bond.
| Bond | N−H\mathrm{N-H}N−H | N≡N\mathrm{N{\equiv}N}N≡N | H−H\mathrm{H-H}H−H |
|---|---|---|---|
| Bond energy (kJ/mol\mathrm{kJ/mol}kJ/mol) | 391 | 945 | 436 |
Calculate the energy change for the reaction.
Use your answer to part (a) to explain what happens to the temperature of the surroundings and where the products would be shown relative to the reactants on a reaction profile.
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.