Alexandra Houff, Crystal Chong
Applied Science, Physics
Material Type:
Preschool, Lower Primary, Upper Primary, Middle School
  • bcpl-training
  • elementary
  • preschool
  • science
  • License:
    Creative Commons Attribution Non-Commercial

    DIY Density Rainbow

    DIY Density Rainbow


    Learn about the liquid density by building a Density Liquid Rainbow.


    This example has only four liquids. You can add more liquids as long as they are arranged most dense to least dense. 


    rainbow jar

    What is density?

    In this project we are going to learn about density and liquids by making a Density Liquid Rainbow made of four liquids of varying densities. Density is a term we use to describe liquid, and it refers to how close or far apart the particles in a liquid are. If a liquid has high density it means the particles are very close together and the liquid is thicker and heavier. Some liquids with high density include dish soap, honey, and molasses. Some liquids with lower density include oil, alcohol, and vinegar.



    For this project you will need:

    • A small jar
    • Dish soap
    • Water
    • Olive oil
    • Some type of rubbing alcohol (I have hand sanitizer)
    • Food coloring
    • Containers to mix in and spoons
    • A butter knife



    To build your Density Rainbow 

    • first pour each of your liquids into separate containers

    containers clear

    • Add the food coloring to the liquids that do not already have any color (if you are using colored dish soap, you can skip the food coloring for that liquid. Likewise the olive oil).

    liquids colored

    • Slowly pour the liquids into the jar, starting with the liquid that is the most dense. The layers in this case would be: 
      • Soap
      • Water
      • Olive Oil
      • Alcohol
    • It's important to pour the layering liquids very slowly. Use the butter knife to control the flow of the liquids.



    Conclusion & How-to Video

    How did our layers stay separated in a rainbow, instead of mixing together? The colors stayed separate because of their different densities. If a liquid has high density it means the particles are very close together and the liquid is more thick and heavy, for example the dish soap. That’s why it settled on the bottom. If a liquid has a lower density it means the particles are farther apart and it’s lighter or thinner, such as the alcohol. That’s why it sits on top.

    Build a Density Rainbow