A student investigated the temperature change during the reaction between malic acid and sodium hydrogencarbonate solution.
Table 1 shows some of the student's results:
| Mass of malic acid added in g\text{g}g | Temperature of solution in ∘C\text{}^\circ\text{C}∘C |
|---|---|
| 0.00 | 22.0 |
| 0.25 | 21.5 |
| 0.50 | 21.0 |
| 0.75 | 20.5 |
| 1.00 | 20.0 |
Explain how the results in Table 1 show that the reaction is endothermic.
The first five data points in Table 1 lie on a straight line of best fit represented by:
T=−2.0m+22.0 T = -2.0m + 22.0 T=−2.0m+22.0where TTT is the temperature in ∘C\text{}^\circ\text{C}∘C and mmm is the mass of malic acid added in g\text{g}g.
For higher masses of malic acid, the reaction is complete, and the mixture begins to warm up. The line of best fit for these points is represented by:
T=0.4m+19.0 T = 0.4m + 19.0 T=0.4m+19.0Determine 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.