A student mixes the reactants for four reactions, A, B, C and D.
The student measures the temperature at the start and at the end of each reaction.
The table shows the results.
| Reaction | Temperature at start (°C) | Temperature at end (°C) |
|---|---|---|
| A: magnesium + hydrochloric acid | 20 | 34 |
| B: citric acid + sodium hydrogencarbonate | 20 | 13 |
| C: sodium hydroxide + hydrochloric acid | 21 | 28 |
| D: barium hydroxide + ammonium chloride | 20 | 2 |
Calculate the temperature change for reaction A.
Temperature change = ...... °C
Which two reactions are endothermic?
Complete the sentences about exothermic reactions.
Use words from the list: decreases, from, increases, stays the same, to
In an exothermic reaction, energy is transferred ...... the surroundings. The temperature of the surroundings ...... .
Give one everyday use of an exothermic reaction.
Give one everyday use of an endothermic reaction.
51 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.