A camp counselor-in-training named Devon collapsed minutes after finishing the "Meltdown Challenge" — chugging a bottle of recovery mix at the end of a winter trek. Core temperature and hydration were normal, so something in the bottle is suspect. You will measure the density of the liquid recovered from Devon's bottle and compare it to tap water and distilled water. Density is an intensive property — it is independent of the amount of substance present.
Click "Measure Volume" to use a graduated cylinder, then "Weigh Sample" to use the scale. Record the readings that appear.
| Sample | Mass (g) | Volume (mL) | Calculated Density (g/mL) | Feedback |
|---|
| Sample | Expected Density | Identity | Interpretation |
|---|---|---|---|
| Unknown Liquid | ~1.25 g/mL | Saturated Epsom Salt (MgSO₄) Solution | Dissolved magnesium sulfate increases mass, raising density well above water. |
| Tap Water | ~1.01 g/mL | Tap Water | Trace minerals slightly raise density above pure water. |
| Distilled Water | ~1.00 g/mL | Distilled Water | Essentially pure H₂O — the standard for density at 25°C. |
For multiplication and division, the answer should have the same number of sig figs as the measurement with the fewest sig figs.
1. Is density an intensive or extensive property? How do you know?
2. The unknown liquid has a higher density than water. What does this suggest about what might be dissolved in it?
3. The camp medic checks a reference chart showing whole blood has a density of about 1.06 g/mL. Based on density alone, could you confuse blood with the liquid from Devon's bottle? What other tests would you do to distinguish them?