Make a Pumpkin Volcano!

October is the perfect month for having fun with pumpkins.

The bright orange fruits make cute decorations and are fun to use in a variety of pumpkin STEM activities.  

If you’re carving pumpkins this year, use one to make a simple pumpkin volcano.   It’s a fun fall twist to an old favorite science experiment.

If you have toddlers or preschoolers, you may want to let them explore whether or not your pumpkin sinks or floats before trying this activity.  

Older kids might enjoy some of these other Halloween STEM activities. 

Pumpkin Volcano Experiment

Materials Needed:

• Pumpkin
• Vinegar
• Baking soda
• Dish soap
• Sharp Knife
• Food coloring (optional)

To begin with, use the knife to remove the top portion of your pumpkin, much like you would when carving pumpkins.  This portion of the activity should be done by an adult.

Then let your child remove the seeds and pulp from the pumpkin.  They can use a spoon or their bare hands, adding a bit of sensory play into the activity.  

Once the pumpkin is hollowed out, sprinkle a healthy dose of baking soda into the bottom of the pumpkin.  How much you need will depend on the size of your pumpkin.  We used 2 Tablespoons for our small pumpkin.  You’ll want to use at least 1/4 cup for a larger pumpkin.  

To increase the amount of bubbles produced, squirt a little bit of dish soap into the bottom as well.  

If desired, you can add a drop or two of food coloring as well.  We chose to leave ours plain. 

When you are ready, slowly pour your vinegar into the pumpkin.  We used 1/2 cup on our small pumpkin.  Larger pumpkins may need a bit more.  

You’ll have an instant volcano in a pumpkin.

For even more fun, try adding pumpkin seeds to the bottom of your pumpkin.  

When the vinegar is added the foam will cause the pumpkin seeds to bubble up and spill out with the pumpkin volcano’s lava.

Does your child love being hands on?  Grab a spoon and let them try stirring. 

Mixing it helps more baking soda react with the vinegar and you get a second eruption.  

This pumpkin STEM activity is so much fun! 

Why Baking Soda & Vinegar Volcano Works

The vinegar is an acid.  The baking soda is a base. 

When these two materials mix, a chemical reaction happens.   

One part of this reaction is that carbon dioxide forms.  This gas causes the bubbling reaction that spills over the sides of the pumpkin.  

For a more detailed explanation, check out this post on why vinegar and baking soda reacts.  

I warn you, this simple Halloween science is addicting.

If your kids are anything like mine, the will ask to do it over and over again.  

We used half a box of baking soda and quite a bit of vinegar before I had to call it quits.  

This simple pumpkin volcano is so easy and so much fun to do in October.  

Other fun fall activities to try:

• Pumpkin Activities — Discover 10 fun activities with real pumpkins. 
• Apple Wrecking Ball STEM Activity — Challenge your child to make a wrecking ball with an apple.
• Vanishing Ghost Experiment — Kids of all ages will have fun with this STEM for Halloween.
• Apple-Scented Bubble Dough— Find out how to make amazing smelling play dough with just 2 ingredients.

Originally published 9/11/2015.