A student investigated the temperature change during the reaction between anhydrous calcium chloride and water.
Table 1 shows some of the student's results:
| Mass of anhydrous calcium chloride added in g\text{g}g | Temperature of solution in ∘C\text{}^\circ\text{C}∘C |
|---|---|
| 0.00 | 18.5 |
| 0.25 | 19.4 |
| 0.50 | 20.3 |
| 0.75 | 21.2 |
| 1.00 | 22.1 |
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=3.6w+18.5T = 3.6w + 18.5T=3.6w+18.5 where TTT is the temperature in ∘C\text{}^\circ\text{C}∘C and www is the mass of anhydrous calcium chloride added in g\text{g}g.
For higher masses of anhydrous calcium chloride, the reaction is complete, and the mixture begins to cool down. The line of best fit for these points is represented by: T=−1.2w+24.5T = -1.2w + 24.5T=−1.2w+24.5
The graph below shows the two lines of best fit:
Determine the overall temperature change for this reaction.