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.
Practise OCR GCSE Chemistry Energetics with exam-style questions for Foundation and Higher tier. 30 questions, matched to the OCR GCSE Chemistry (J248) specification and written in Paper 1 and Paper 2 (Foundation Tier) or Paper 3 and Paper 4 (Higher Tier) style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.