Spooky Foaming JACK-O’-LANTERN Pumpkin Experiment

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Do you have a leftover Jack-O-Lantern at home? Let your future chemist or biologist perform an experiment before you trash it. Try this Spooky Foaming JACK-O’-LANTERN Pumpkin Experiment at home!

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

One of our spooky foaming Jack-O-Lantern pumpkins!

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


  • 1 cup of hydrogen peroxide12
  • 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
  • lab apron
  • nitrile gloves


  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 Spooky Foaming JACK-O’-LANTERN Pumpkin!

(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 to your Spooky Foaming JACK-O’-LANTERN Pumpkin?

The reaction that occurs is an exothermic chemical reaction (which also involves some biology)! Hydrogen peroxide is chemically H2O2. When it breaks down it turns into water and oxygen. The bubbles are formed by oxygen gas. Yeast acts as a catalyst. This means it causes the experiment to happen faster. The soap creates really fun bubbly foam!

For more details check out my reference at https://www.scientificamerican.com/article/make-elephant-toothpaste/

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.

I hope you enjoy! Are you looking for more Halloween STEAM activities? Check them our here!


  1. If you compost your pumpkin please be sure that you wash out all the chemical from the pumpkin thoroughly as chemicals cold seriously hurt wildlife if they try to eat it. ↩︎
  2. We used 3% hydrogen peroxide. A more concentrated hydrogen peroxide will yield a faster chemical reaction, which might also be hot to touch initially. So be sure to wear safety gear. ↩︎

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