Chemist, Experiments, Halloween, Holiday, Inexpensive and Versatile, STEM Resources

Foaming JACK-O’-LANTERN Experiment

Do you have a leftover Jack-O-Lantern at home? Let your future chemist or biologist perform an experiment before you trash it!

We recently made our spooky Jack-O-Lantern’s foam from the mouth and the kids LOVED it.

If you want to try this at home, here is what we did!

What you need:

– 1 cup of hydrogen peroxide*

– 2 tablespoons of dish soap

– food coloring

– 6 tablespoons of warm water

– 0.5 tablespoons of dry yeast or one packet of yeast

– one 16 ounce cylinder (we ended up using a disposable coffee cup)

– one cup for mixing yeast

– two spoons

– goggles

What do you do:

1. Pour hydrogen peroxide into the cylinder.

2. Pour dish soap into the cylinder.

3. Add a few drops of any color food coloring.

4. Mix with a spoon. Place the cylinder in the Jack-O-Lantern.

5. Place dry yeast in warm water and mix for at least 30 seconds.

6. Pour the yeast mixture into the peroxide mixture and watch your pumpkin foam.

(Be careful when removing the cylinder, some of the mixture might be hot depending on the peroxide you used. Give the foam time to cool down because this is an exothermic reaction and it will initially be hot.)

What’s happening?

An exothermic chemical reaction and also involves done biology! Hydrogen peroxide is chemically H2O2. When it breaks down it turns into H2O and O. Yeast helps it break down sooner because it contains something called catalase which is a catalyst. Oxygen gas forms the bubbles that would normally pop quickly. Adding the soap let’s the reaction look like really fun bubbly foam!

For more details check out my reference at

If your pumpkin is large like ours, you might need to double the recipe. We used the original recipe and wish that we would have doubled or even tripled it.

*We also only used 3% hydrogen peroxide. If you use a higher amount like 6% or 12%, you may need to experiment a bit. A more concentrated hydrogen peroxide (higher percentage) will yield a faster chemical reaction.

I hope you enjoy! Tag me on social media if you try this out!

Note: If you compost your pumpkin please be sure that you wash out all the chemical from the pumpkin thoroughly as the chemicals could seriously hurt wildlife if they try to eat it.


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