Fireworks in a Jar

This science experiment uses oil and water to create fireworks in a jar! Kids will love learning about density and how oil and water do not mix in this fun and easy science experiment!

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Fireworks in a Jar Experiment

This fireworks in a jar experiment explores density using oil and water. This is also a fun experiment to try for the 4th of July, Memorial Day or New Years Eve!

What is Density?

Density is the amount of mass per unit of volume. Let’s say you have two objects and they are the same size. If one object is heavier, then it is denser and if the other object is lighter, then it is less dense.

What you will see in this experiment is that oil is less dense than water, so it will float on top of the water.

The Science Behind It

Oil and water do not mix. Oil is less dense than water and floats on top of the water. Food coloring is water-based so it mixes with the water. When you add the food coloring to the oil it will not mix. Once you add the oil to the water, the food colored droplets start to drop down since they are heavier than the oil. Once they drop into the water they start to dissolve and look like tiny explosions (or fireworks).

Watch the Video Tutorial!

Supplies Needed

• Water

• Vegetable Oil – we used canola oil

• Food Coloring – we used red and blue. You want regular, water-based food coloring for this experiment

• A Clear Jar

Steps to do a Fireworks in a Jar Experiment

1. Fill your jar or vase 3/4 full with water.

2. Add oil into a bowl.

You do not need a lot of oil– you can use about 4 tablespoons of oil for a thin layer. A little more oil will show the difference in density slightly better for kids.

3. Add 3-4 drops of red and blue food coloring.

You can use any colors you’d like but we would recommend no more than 3 as the colors will mix quickly and will make it harder to see them dropping down.

4. Whisk the food coloring into the oil.

You can point out at this stage that you can already tell the oil and water will not mix.  It’s best to whisk and add the oil straight into the jar before the food coloring settles on the bottom of the bowl or or it may not form droplets when you add it to the water.

5. Add the oil into the water.

Now wait and see all of the little drops start to come down from the oil (making “fireworks”).

We love how easy this simple science experiment is – and kids will love to observe or make their own fireworks in a jar too!

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