Rainbow in a Jar Science Experiment

Want to make your own rainbow? In this simple science experiment, kids can build their own rainbow in a jar while exploring density, mass, and volume.

Watch our demonstration video, gather your supplies, and print out our detailed instructions to get started. An easy to understand explanation of how it works is included below.

JUMP TO SECTION: Instructions | Video Tutorial | How it Works

Supplies Needed

• Tall Glass Jar
• Food Coloring: Red, Blue and Green
• 1/4 cup Honey
• 1/4 cup Blue Dish Soap
• 1/4 cup Water
• 1/4 cup Olive Oil
• 1/4 cup Rubbing Alcohol
• Jars for mixing and pouring
• Teaspoons for mixing

Rainbow in a Jar Science ExperimentInstructions

Step 1 – Add one drop of red food coloring and one drop of blue food coloring to 1/4 cup of honey and stir until combined. This creates a purple color liquid. Pour the purple liquid carefully into the tall jar.

Step 2 – Next add about 1/4 cup of blue dish soap to the tall jar.

Step 3 – Add a few drops of green food coloring to 1/4 cup of water and mix until combined. Then, carefully pour the green liquid into the tall jar. Tip: When pouring in the green liquid, tilt the jar so the liquid runs down the side of the jar slowly.

Step 4 – Wait a few moments and then slowly pour 1/4 cup of olive oil into the jar. Again, be very careful when pouring in the liquid. Make sure to tilt the jar and pour very slowly so the colors don’t mix.

Step 5 – Add a few drops of red food coloring to 1/4 cup of rubbing alcohol and mix until combined. Then, carefully pour the red liquid into the tall jar. Tip: I can’t stress enough how important it is to tilt the jar and pour slow. Otherwise, the colors will mix together and you won’t get a distinct rainbow.

Do you know why you were able to make the liquids form the rainbow in a jar? Find out the answer in the how does this experiment work section below.

Video Tutorial

Detailed Rainbow in a Jar Science Experiment Step by Step Instructions

How Does the Science Experiment Work

Why did the liquids stay in separate layers?

This experiment works because each liquid has a different density.

Density is a measure of how much matter is packed into a certain amount of space. Some liquids have a higher density, which means they are heavier for the same amount of space. Other liquids have a lower density, which means they are lighter.

When you carefully pour the liquids into the jar, the liquid with the highest density sinks to the bottom. Liquids with lower densities float on top of the denser liquids. This creates colorful layers that look like a rainbow.

Each liquid has its own unique density. In this experiment, honey is the most dense liquid, so it settles at the bottom. Dish soap, water, olive oil, and rubbing alcohol each form their own layer because they have different densities.

Scientists use density to predict whether one substance will float or sink in another.

I hope you enjoyed the experiment. Here are some printable instructions:

Rainbow in a Jar Science Experiment

Print

Materials

• Tall Glass Jar
• Food Coloring: Red, Blue and Green
• 1/4 cup Honey
• 1/4 cup Blue Dish Soap
• 1/4 cup Water
• 1/4 cup Olive Oil
• 1/4 cup Rubbing Alcohol
• Jars for mixing and pouring
• Teaspoons for mixing

Instructions

1. Add one drop of red food coloring and one drop of blue food coloring to 1/4 cup of honey and stir until combined. This is create a purple color liquid. Pour the purple liquid carefully into the tall jar.
2. Next add about 1/4 cup of blue dish soap to the tall jar.
3. Then add a few drops of green food coloring to 1/4 cup of water and mix until combined. Then carefully pour the green liquid into the tall jar. Tip: When pouring in the green liquid, tilt the jar so the liquid runs down the side of the jar slowly.
4. Wait a few moments and then slowly pour 1/4 cup of olive oil into the jar. Tip: Again, be very careful when pouring in the liquid. Make sure to tilt the jar and pour very slowly so the colors don’t mix.
5. Add a few drops of red food coloring to 1/4 cup of rubbing alcohol and mix until combined. Then carefully pour the red liquid into the tall jar. Tip: I can’t stress enough how important it is to tilt the jar and pour slow. Otherwise the colors will mix together and you won’t get a distinct rainbow.