Rainbow in a Jar Density Experiment

Questions to explore:

How can we test the density of different liquids?

How can we use chemicals to make a rainbow in a jar?


  • 1 mason jar
  • 1/2 cup blue dishwashing liquid
  • 1/2 cup olive oil (or Canola oil)
  • 1/2 cup rubbing alcohol
  • 1/2 cup light corn syrup (or honey)
  • Food coloring (many colors)
  • 5 spoons
  • a beaker
  • a turkey baster (or eye dropper)
  • 5 bowls for mixing


  1. Make your purple layer by mixing 1/2 cup of the light corn syrup with 1 drop of blue and 1 drop of red food coloring.
  2. Use the beaker to carefully pour the corn syrup into the bottom center of your jar. Make sure it doesn’t touch the sides!
  3. Carefully pour the blue dish soap down the side of the jar. You may slightly tilt your jar for this part or use a turkey baster to pour the dish soap slowly and carefully.
  4. Mix 1/2 cup of water with 2 drops of green food coloring.
  5. Carefully pour in your green water down the side of the jar.
  6. Gently pour 1/2 cup olive oil down the side of your jar.
  7. Mix 1/2 cup of rubbing alcohol with 2 drops of red food coloring.
  8. Carefully pour the red rubbing alcohol down the inside of your jar.
  9. Carefully set your jar down on the table and enjoy your rainbow!

Follow up questions:

Why didn’t these liquids mix together?

What would happen if I turned the jar upside down?

What other liquids would you like to explore?

Make sure to draw and label your results!


How are all of these layers able to remain separate?  The reason the liquids do not mix is because they have different density levels.  Density is defined as the amount of mass per volume in a liquid.  Liquids that are more dense have molecules that are more tightly packed.  Liquids that are less dense have molecules that are further apart. Dense liquids, such as corn syrup, are heavier, and therefore sit nicely on the bottom of the tower. As the tower goes up, each liquid is less and less dense, causing distinct lines to remain between each liquid.


Experiment Credit: https://www.education.com/science-fair/article/rainbow-in-a-jar/


To see this experiment in action, watch the following video by the Sci Guys! (The Sci Guys use even more liquids than we do, so feel free to try experimenting with various liquids!)




Featured photo: https://www.youtube.com/watch?v=OefYSL0jLcg

Materials photo: http://www.mykidsadventures.com/how-to-stack-liquids/