As I was trying to think of a science experiment to do with Peeps, I remembered seeing a marshmallow puff up to twice its normal size in a vacuum chamber, which was pretty cool.
Since I don’t have any way to create a mechanical vacuum at home, I decided to try using a wine pump to inflate a peep and discovered that it is extremely hard to get a Peep into a wine bottle. Even the bunny Peeps are too big to push in without maximum destruction!
So, I went bottle hunting and found that Smucker’s syrup bottles and Martinelli’s apple juice bottles have big enough mouths to accommodate Peeps of the chick or bunny variety, but still work with wine pumps. Here’s what happened!
To puff up a Peep, you’ll need
-a clear, empty bottle that fits both a Peep and a wine pump (see above.)
-a wine pump with a matching rubber vacuum cork
-Peeps (or marshmallows)
- Put a Peep or two in the bottle. If it’s sticky, coat the sticky spot with a little bit of sugar. Try to squish it as little as possible when pushing it into the bottle.
- Put the rubber vacuum cork in the bottle to form a tight seal.
- Pump air out of the bottle until your Peep has grown as much as possible
- Release the vacuum to see it shrink back to normal size.
The Science Behind the Fun:
Peeps contain corn syrup, gelatin and food coloring, but they are mostly made up of air bubbles. The air trapped in the bubbles is at atmospheric pressure. When you pump air out of the bottle, the pressure in the bottle drops. Gases expand under lower pressure, and the air in the marshmallow bubbles is no exception. The bubbles expand inside the stretchy corn syrup and gelatin (get bigger), making the Peep puff up.