The table below shows the results of two chemical reactions, C and D.
| Temperature at the start of the reaction (∘C^\circ\text{C}∘C) | Temperature at the end of the reaction (∘C^\circ\text{C}∘C) | Energy change (kJ/mol\text{kJ/mol}kJ/mol) | |
|---|---|---|---|
| Reaction C | 21.8 | 28.4 | -185 |
| Reaction D | 22.5 | 16.1 | +312 |
Use the information in the table to state whether each of the reactions, C and D, is exothermic or endothermic. Explain your answers with reference to both the temperature changes and the energy changes.
A student performs another reaction in an open glass beaker but finds that the measured temperature change is smaller than expected due to heat escaping to the surroundings. Suggest two ways they can improve their experimental apparatus to minimize heat transfer.
15 exam-style questions on OCR GCSE Chemistry Energetics. Each one has a worked solution and a mark scheme showing where the marks go.