This activity will demonstrate that liquids with different densities
are separated by the force of gravity.
Time requirement: 30 minutes as an activity, 15 minutes as a demonstration.
- 1 200 ml graduated cylinder
- 1 100 ml beaker
- Food coloring (two colors)
- Salt water
- Dish washing soap
- Rubbing alcohol
- Pour 20 ml of glycerin into the graduated cylinder. Add a drop or two
of food coloring to make the liquid more visible.
- Add 20 ml of salt water to the 100 ml beaker. Add a drop or two of the
other food coloring. Carefully add the 20 ml of salt water to the
- Carefully add 20 ml of the dish soap to the graduated cylinder.
- Add 20 ml of fresh water to the graduated cylinder.
- Add a small amount of the alcohol to the graduated cylinder.
- Describe what happened when each of the liquids was added to the
- Describe the boundary between the different liquids.
- Why do the liquids separate? Why do some of the liquids move toward
the bottom of the cylinder and some liquids toward the top?
- Which liquids might be mixing and why?
- Over time, will the liquids mix or remain separated?
Last updated: August 27, 1997
Joe Twicken /