A student investigates the temperature changes during three different chemical reactions using mixtures X, Y, and Z.
Complete the table below by calculating the temperature change for each reaction mixture. Make sure to include a +++ or −-− sign where appropriate.
| Reaction mixture | Temperature at start (°C) | Temperature at end (°C) | Temperature change (°C) |
|---|---|---|---|
| X | 21.8 | 13.4 | ……………\dots\dots\dots\dots\dots…………… |
| Y | 19.3 | 32.1 | ……………\dots\dots\dots\dots\dots…………… |
| Z | 20.0 | 20.0 | ……………\dots\dots\dots\dots\dots…………… |
Which reaction mixture represents an endothermic reaction? Explain your answer.
The combustion (burning) of pentane liquid, C5H12\text{C}_5\text{H}_{12}C5H12, is an exothermic reaction. When pentane burns completely in oxygen, O2\text{O}_2O2, it produces carbon dioxide, CO2\text{CO}_2CO2, and water, H2O\text{H}_2\text{O}H2O.
Write the balanced symbol equation for this reaction.
15 exam-style questions on OCR GCSE Chemistry Energetics. Each one has a worked solution and a mark scheme showing where the marks go.