In an investigation of the heat energy changes during an endothermic neutralisation reaction, a student added varying masses of anhydrous citric acid to separate 50 cm3 samples of sodium hydrogencarbonate solution. The maximum temperature decrease produced by each mass of citric acid was recorded.
The student's data is shown in the table below:
| Mass of citric acid added (mmm) / g\text{g}g | Maximum temperature decrease (ΔT\Delta TΔT) / ∘C^\circ\text{C}∘C |
|---|---|
| 1.5 | 4.2 |
| 3.0 | 7.6 |
| 4.5 | 10.2 |
| 6.0 | 12.0 |
| 7.5 | 13.1 |
Draw a graph of the maximum temperature decrease (ΔT\Delta TΔT) on the vertical axis against the mass of citric acid added (mmm) on the horizontal axis.
94 exam-style questions on Edexcel GCSE Chemistry 8.2 Heat energy changes in chemical reactions, covering 8.2.1 Exothermic and endothermic changes, 8.2.2 Bond breaking, bond making and overall energy change, 8.2.3 Calculating energy change from bond energies, and 8.2.4 Activation energy and reaction profiles. Each one has a worked solution and a mark scheme showing where the marks go.