Hydrogen reacts with fluorine to make hydrogen fluoride: H2+F2\text{H}_2 + \text{F}_2H2+F2 goes to 2HF2\text{HF}2HF
Table: The bond energies of the bonds in the reactants and in the product
| Bond | Bond energy in kJ/mol |
|---|---|
| H-H\text{H-H}H-H | 436 |
| F-F\text{F-F}F-F | 158 |
| H-F\text{H-F}H-F | 562 |
Calculate the energy needed to break all of the bonds in the reactants.
Calculate the energy released when all of the bonds in the product are formed.
Calculate the overall energy change of the reaction.
Explain how your answer to part c shows that the reaction is exothermic.
39 exam-style questions on AQA GCSE Chemistry 5.1 Exothermic and endothermic reactions, covering 5.1.1 Energy transfer during exothermic and endothermic reactions, 5.1.2 Reaction profiles, and 5.1.3 The energy change of reactions. Each one has a worked solution and a mark scheme showing where the marks go.