A student investigated the temperature change during the reaction between magnesium ribbon and dilute hydrochloric acid.
Table 1 shows some of the student's results:
| Mass of magnesium added in g\text{g}g | Temperature of solution in ∘C\text{}^\circ\text{C}∘C |
|---|---|
| 0.00 | 18.0 |
| 0.20 | 20.4 |
| 0.40 | 22.8 |
| 0.60 | 25.2 |
| 0.80 | 27.6 |
Explain how the results in Table 1 show that the reaction is exothermic.
The first five data points in Table 1 lie on a straight line of best fit represented by:
T=12.0m+18.0 T = 12.0m + 18.0 T=12.0m+18.0where TTT is the temperature in ∘C\text{}^\circ\text{C}∘C and mmm is the mass of magnesium added in g\text{g}g.
For higher masses of magnesium, the hydrochloric acid has completely reacted, and the mixture begins to cool down. The line of best fit for these points is represented by:
T=−3.0m+31.5 T = -3.0m + 31.5 T=−3.0m+31.5Determine the overall temperature change for this reaction.
13 exam-style questions on AQA GCSE Chemistry 5.1 Exothermic and endothermic reactions, covering 5.1.1 Energy transfer during exothermic and endothermic reactions, 5.1.2 Reaction profiles, and 5.1.3 The energy change of reactions (HT only). Each one has a worked solution and a mark scheme showing where the marks go.