A student investigated the heat energy released during the combustion of various liquid alkanes. In each experiment, the student burned exactly 0.5 g of the alkane to heat 150 cm3 of water in a simple calorimeter. The temperature rise of the water was recorded for each alkane.
| Alkane | Number of carbon atoms in one molecule | Temperature rise of water in ∘C^\circ\text{C}∘C |
|---|---|---|
| pentane | 5 | 14.5 |
| hexane | 6 | 20.0 |
| heptane | 7 | 24.5 |
| octane | 8 | 28.0 |
| nonane | 9 | 30.5 |
Draw a graph of the temperature rise of the water against the number of carbon atoms in one molecule of the alkane.
94 exam-style questions on Edexcel GCSE Chemistry 8.2 Heat energy changes in chemical reactions, covering 8.2.1 Exothermic and endothermic changes, 8.2.2 Bond breaking, bond making and overall energy change, 8.2.3 Calculating energy change from bond energies, and 8.2.4 Activation energy and reaction profiles. Each one has a worked solution and a mark scheme showing where the marks go.