- Grab a pumpkin! You can use just about any pumpkin, white or orange. Baking pumpkins are usually a great size, and you can pick them up in your local grocery store. A bigger pumpkin will work, but you will need more baking soda and vinegar.
An adult should use a knife to cut a hole in the top of the pumpkin. Next, you will want to clean out the guts. Then you will want to carve your puking pumpkin face.
Put about 1/4 of a cup of baking soda into the pumpkin.
- Add a squirt of dish soap if you want a foamier eruption! The chemical eruption will produce frothier bubbles with the added dish soap and create more overflow too.
Add a few drops of food coloring. You can also add food coloring to the vinegar for a deeper color eruption.
Time to add the vinegar and observe the chemistry at work!
TIP: Put your vinegar into a container that is easy for small hands to squirt or pour into the pumpkin.
When you mix baking soda and vinegar together, you get a foamy explosion! Why does this happen? Vinegar is an acid, which means it scores less than a 7 on the pH scale. Baking soda, on the other hand, is a base. Bases are the opposite of acids - they score more than 7 on the pH scale. When these two opposites mix together, they make carbon dioxide gas. The gas is full of tiny bubbles that make the mixture foam and "explode."
- What do you think will happen if you try this experiment with baking soda and a different acid, like lemon juice? Will it make the same foam for the pumpkin to "puke?"
- What happens if you change the amounts of baking soda and vinegar used? For example, what do you think would happen if you used less vinegar and more baking soda? What if you used more vinegar and less baking soda?