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Erupting Pumpkins


Erupting Pumpkins

By Adventure Science Center

Double, double toil and trouble, fire burn and pumpkin bubble? Get in the Halloween spirit with this fun, chemistry-based sensory activity based on a timeless classic: volcanoes!


  • Reaction–
    (noun) chemical transformation or change : the action between atoms or molecules to form one or more new substances.
  • Erupt–
    (verb) to burst forth or cause to burst forth.
  • Carbon Dioxide–
    (noun) a heavy colorless gas that does not support burning, dissolves in water to form carbonic acid, is formed especially by the burning and breaking down of organic substances (as in animal respiration), is absorbed from the air by plants in photosynthesis, and has many industrial uses.
  • Volcano–
    (noun) a vent in the earth’s crust from which melted or hot rock and steam come out.


  • Small pumpkin
  • Baking soda
  • Vinegar
  • Food coloring (optional)
  • Dish soap
  • Warm water

NOTE: The bigger your pumpkin, the more baking soda and vinegar you will need and the bigger mess you will make! 


  1. Take your pumpkin and hollow it out. You can save the insides for additional sensory play, or to make roasted pumpkin seeds for a healthy treat!
  2. Place your hollow pumpkin in a large dish or pan to keep the mess (mostly) contained.
  3. Decide whether you want to create the reaction in the pumpkin itself or in a container inside your hollow pumpkin. Create the following mixture:
    • Fill your container/pumpkin with warm water mixed with food coloring (optional) to about ¾ full.
    • Add 4-5 drops of dish soap.
  4. When you’re ready to make your pumpkin erupt:
    • Add a few tablespoons of baking soda to your mixture, then get ready…
    • Add ¼ cup of vinegar and step back as your pumpkin-cano erupts!

Further Exploration

Test out different explosions using different containers in your pumpkin. What happens when you use a bottle? What about a cup? What’s really happening in this pumpkin-cano?

Well, the eruption is a result of a reaction between the baking soda and vinegar. Carbon dioxide gas is produced, pressure builds up until the gas bubbles out of the pumpkin! Carbon dioxide is also present when real volcanoes erupt.




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