Skip to content
Grades 6–8 Beginner About 10 min Version 1 Awaiting review Premium

Density: build a liquid tower

Density tells us how much mass is packed into a certain volume. A liquid with a high density is "heavier for its size". When liquids that do not mix quickly are poured into the same container, the densest one sinks to the bottom and the least dense one floats on top.

What you will learn

  • Describe density as how much mass is packed into a volume.
  • Predict the order of liquid layers from their densities.
  • Explain why the pouring order does not change the final layers.

Before you start

  • Know how to read volume in millilitres (mL).

Materials

  • Honey
  • Dish soap
  • Water with blue food colouring
  • Vegetable oil

Equipment

  • 2 measuring cylinders (100 mL)

Procedure

  1. Pour 20 mL of each liquid into Cylinder A, slowly, in any order.
  2. Observe the layers after each pour.
  3. Fill Cylinder B with the same four liquids, but pour them in a different order.
  4. Compare the two cylinders.

How this simulation is simplified

  • Liquids are poured slowly and not stirred. Honey, dish soap and water would slowly mix if stirred. Oil never mixes with water.
  • Each liquid moves to its layer straight away. In real life, honey takes a few seconds to sink through other liquids.