The temperature is steady before mixing. It then rises to a maximum and starts to fall as energy transfers to the room. For these example results: 31 − 20 = 11 °C. The later cooling does not mean that the neutralisation became endothermic.
| Acid (mol/dm³) | Rise 1 (°C) | Rise 2 (°C) | Rise 3 (°C) | Mean (°C) |
|---|---|---|---|---|
| 0.2 | 1.3 | 1.4 | 1.5 | 1.4 |
| 0.4 | 2.6 | 2.7 | 2.8 | 2.7 |
| 0.6 | 4.0 | 4.1 | 4.2 | 4.1 |
| 0.8 | 5.3 | 5.4 | 5.5 | 5.4 |
These are separate example trials of the concentration investigation. Mean = total ÷ number of readings. Plot concentration on the x-axis and mean temperature rise on the y-axis. In this range, increasing acid concentration increases the rise: more acid particles react in the same volume, with enough alkali available.
Energy lost to the room makes the measured maximum and temperature rise too low. Improve insulation and replace the lid quickly. Repeats help check random variation; they do not remove energy loss.
An anomalous result does not fit the other results. Check the method and repeat it. Only exclude a result with a justified reason; do not remove data just because you dislike it.
A larger temperature rise means more energy transferred only in a fair comparison with the same amount and type of solution.
Use the peak, calculate means, check anomalies and explain why insulation improves the measurement.
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