Your average jack o’lantern is usually a cool face carved into a nice, big pumpkin (which is actually a fruit from the same plant family as cucumber and melon, by the way). We carve pumpkins at the Discovery Centre just like everyone else does, but sometimes we make something other than light come out of them. In fact, we like to make our pumpkins spew! Which may sound gross, but trust us, your kids will love it!
If you would like to try this experiment at home, you will need: a carved pumpkin, some dish soap, some dry yeast and some hydrogen peroxide (more on that below). Food colouring is optional!
Take a tablespoon or so of yeast and mix it with warm water – enough to make it a little runny. Next, pour some peroxide into your pumpkin – if your pumpkin is fist-sized, a few tablespoons will be enough, but for larger pumpkins you may need a small container inside to hold everything. Add a good squirt of dish soap to your peroxide (and colour if you like), and then quickly pour in some of your yeast. Foam should pour slowly out of the openings in your pumpkin giving the illusion of a spewing or “puking” pumpkin, as kids like to say. Yes it’s gross, but fun!
The foam coming from your pumpkin is filled with oxygen, which is produced by hydrogen peroxide as it breaks apart into water and oxygen gas. The yeast you added speeds this up because of natural chemicals it contains. The bigger the pumpkin, the more ingredients you’ll need, and the stronger the peroxide, the faster the spewing will go. First-aid peroxide is about 3% concentration, but you can get 6% (or “20 volume”) for bleaching hair. The stronger it is, the more likely it will bother your skin or eyes though, so an adult should handle the high-test stuff.
With our help, the neighbourhood kids on your block will think you have the coolest pumpkins! For more Halloween fun, join us on October 29 from 5:30 – 8:30 p.m. for Discovery Centre’s Spooktacular Science Halloween Party. It’s bound to be a scream.