Passage
Students timed how long a sugar cube takes to dissolve completely in water. In each trial they dropped one identical sugar cube into 200 mL of water and recorded the time in seconds until no sugar could be seen.
Study 1: Leaving the water still (not stirred), the students used water at different temperatures and recorded the dissolving time (Table 1).
| Water temperature (°C) | Dissolving time (s) |
|---|
| 10 | 240 |
| 20 | 150 |
| 30 | 95 |
| 40 | 62 |
| 50 | 45 |
Study 2: Holding the water temperature at 30°C, the students stirred the water at different speeds and recorded the dissolving time (Table 2).
| Stirring speed (stirs per second) | Dissolving time (s) |
|---|
| 0 | 95 |
| 1 | 60 |
| 2 | 42 |
| 3 | 33 |
The same size of sugar cube and the same amount of water were used in every trial.
