Layering Liquids

Time requirement: 30 minutes as an activity, 15 minutes as a demonstration.

Materials

• 1 200 ml graduated cylinder
• 1 100 ml beaker
• Food coloring (two colors)
• Glycerin
• Salt water
• Dish washing soap
• Water
• Rubbing alcohol

Procedures

1. Pour 20 ml of glycerin into the graduated cylinder. Add a drop or two of food coloring to make the liquid more visible.
2. 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 graduated cylinder.
3. Carefully add 20 ml of the dish soap to the graduated cylinder.
4. Add 20 ml of fresh water to the graduated cylinder.
5. Add a small amount of the alcohol to the graduated cylinder.

Observation questions

1. Describe what happened when each of the liquids was added to the graduated cylinder.
2. Describe the boundary between the different liquids.
3. Why do the liquids separate? Why do some of the liquids move toward the bottom of the cylinder and some liquids toward the top?
4. Which liquids might be mixing and why?
5. Over time, will the liquids mix or remain separated?