A student investigated the temperature change when different masses of anhydrous copper(II) sulfate were dissolved in 50 cm350\text{ cm}^350 cm3 of water.
Table 1 shows the student's results:
| Mass of anhydrous copper(II) sulfate added (g\text{g}g) | Highest temperature of solution (∘C^\circ\text{C}∘C) |
|---|---|
| 1.5 | 23.8 |
| 3.0 | 28.1 |
| 4.5 | 32.4 |
| 6.0 | 36.7 |
| 7.5 | 41.0 |
Assuming a linear relationship, calculate the initial temperature of the water (the temperature where the mass of copper(II) sulfate added is 0 g0\text{ g}0 g).
The student then repeated the experiment four times with 4.5 g4.5\text{ g}4.5 g of copper(II) sulfate to check the reliability of the results. Table 2 shows these repeat trials:
| Trial 1 (∘C^\circ\text{C}∘C) | Trial 2 (∘C^\circ\text{C}∘C) | Trial 3 (∘C^\circ\text{C}∘C) | Trial 4 (∘C^\circ\text{C}∘C) |
|---|---|---|---|
| 32.1 | 32.9 | 32.3 | 32.7 |
Calculate the mean highest temperature and express the result with its uncertainty in the form mean±uncertainty\text{mean} \pm \text{uncertainty}mean±uncertainty, where the uncertainty is calculated as half of the range.