The Puking Pumpkin: The Perfect STEAM Project to Celebrate Halloween.


This is a spooky Halloween twist on the classic volcano science project that will delight the young scientists in your life. This time around we are going to use a carved pumpkin as the vessel for our baking soda and vinegar explosion, resulting in a jack-o-lantern that looks like it’s vomiting.

Here are the supplies you’ll need for this project:

  • One carved pumpkin
  • Baking soda
  • Vinegar
  • Food coloring
  • A mixing vessel
  • An outdoor space you don’t mind getting a little messy

Halloween Puking Pumpkin Experiment: Step-by-Step Fun!

  1. Get Carving!
    Start by carving your pumpkin. Cut a hole in the top, then scoop out all the gooey, slimy guts (gross but fun, right?). Now, carve a silly or spooky face on your pumpkin — just make sure it has a big mouth ready for the “puking” action! Tip: Do this project outside, somewhere easy to clean — you’re going to need a hose!
  2. Add the Magic Powder!
    With the pumpkin lid off, pour about ½ cup of baking soda inside. Adjust the amount based on how wild you want the eruption to be!
  3. Mix Up the Magic Potion!
    In a separate container, mix vinegar with a few drops of orange food coloring (or any color you like — get creative!). We used around 2 cups of vinegar, but you don’t need to be exact. Let your kids play around with the ratios and see what happens!
  4. It’s Eruption Time!
    Now, the moment you’ve been waiting for — slowly pour the vinegar into the pumpkin and stand back. Watch as your pumpkin “vomits” foam in an epic eruption!  (Warning: Don’t let it overflow before you’re ready!)
  5. Do It Again (and Again)!
    Want more fun? Add more vinegar and make your pumpkin puke over and over. The messier, the better — this is science at its messiest (and coolest)!

The Science Behind the “Puking Pumpkin”

In this experiment, we create a “puking pumpkin” or eruption by combining an acid (vinegar) with a base (baking soda) inside a pumpkin. Pumpkins themselves aren’t naturally acidic — you can tell by tasting them or using a pH test. To trigger the eruption, we add vinegar (the acid) and baking soda (the base), which react and create a dramatic eruption.

The formula is simple: Pumpkin + Baking Soda + Vinegar = Puking Pumpkin!

For a more scientific explanation, here’s the chemical reaction:

CH₃COOH (l) + NaHCO₃ (s) → CH₃COONa (aq) + CO₂ (g) + H₂O (l)

  • Vinegar (acetic acid) has the formula CH₃COOH.
  • Baking soda (sodium bicarbonate) is NaHCO₃.

When combined, they produce sodium acetate (CH₃COONa), along with carbon dioxide (CO₂) and water (H₂O). The carbon dioxide gas causes the bubbling and foaming that make our pumpkin “puke.”

 

Resources:

  • Download the companion worksheet here!
  • Looking for more project-based learning ideas? Click here!