Oozing Pumpkins – Sick Science!

A new experiment to add a fun twist to your jack-o-lantern

It's an awesome new Halloween twist on our Kid-Friendly Elephant's Toothpaste experiment! With this demonstration, you'll have an awesome foaming ooze seeping from the face of your jack-o-lantern and squeals of excitement coming from the face of your audience.


  • Hydrogen peroxide - 12% (You can find this in the hair care section.)
  • Liquid dish soap
  • Food coloring
  • Package of dry yeast
  • Small cup (make sure it's small enough to fit all the way in your pumpkin)
  • Don't forget... a small carved pumpkin


  1. Fill a small cup with 30 mL of hydrogen peroxide (12%).
  2. Add a squirt of dish soap to your hydrogen peroxide.
  3. Mix in some some food coloring to give your reaction a bit of effect.
  4. Open up the top of your jack-o-lantern and carefully lower the cup of mixture into the jack-o-lantern. Don't tip it over or you'll have to start over from the beginning.
  5. Now you're going to need to create your Elephant's Toothpaste catalyst. Mix an entire package of dry yeast with 4 tablespoons of very warm water in a small plastic cup. If the mixture is too thick, like a paste, add a little more warm water to thin it out.
  6. Pour the yeast solution into the cup and quickly replace the top of your jack-o-lantern. It may take a few seconds, but once the reaction starts the result is well worth the wait.

How Does It Work?

In this reaction, you've got a catalyst in the form of your yeast solution. This catalysts works to release the oxygen molecules that are contained in the hydrogen peroxide. Those molecules are being released as the hydrogen peroxide breaks down into two components, water (H2O) and oxygen (O2), from the addition of the yeast catalyst. The foam is the molecules of oxygen being made into tiny bubbles as they pass through the soap that your added.  In addition, as the bonds break between the H2O and O2, they release energy in the form of heat. Try performing the experiment without the pumpkin and feel the sides of the cup. They're warm!