A data sheet gives information for the reaction below.
O2+2F2→2OF2 \mathrm{O_{2} + 2F_{2} \rightarrow 2OF_{2}} O2+2F2→2OF2| Substance | Displayed formula | Number in equation |
|---|---|---|
| O2\mathrm{O_{2}}O2 | O=O\mathrm{O{=}O}O=O | 1 |
| F2\mathrm{F_{2}}F2 | F−F\mathrm{F{-}F}F−F | 2 |
| OF2\mathrm{OF_{2}}OF2 | F−O−F\mathrm{F{-}O{-}F}F−O−F | 2 |
| Bond | O=O\mathrm{O{=}O}O=O | F−F\mathrm{F{-}F}F−F | O−F\mathrm{O{-}F}O−F |
|---|---|---|---|
| Bond energy (kJ/mol\mathrm{kJ/mol}kJ/mol) | 498 | 158 | 190 |
An experimental measurement gives an energy change of +48 kJ/mol for the equation as written.
Calculate the energy change for this reaction using the bond-energy data.
Compare the calculated value with the experimental value and suggest why they are different.
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.