Massive Marshmallows

I love marshmallows; they taste great in cookies, s’mores, and by themselves. But what’s even better than a normal marshmallow? A massive marshmallow! This experiment takes a normal marshmallow and puffs it up to almost 4 times its original size.

What you need:

• 3 marshmallows
• Plate
• Microwave

Steps:

• Place two marshmallows on the plate

• Place the plate in the microwave and watch the marshmallows expand to your desired size (this will only take a few seconds, so make sure to keep a close eye on them)
• Take the marshmallows out of the microwave. Compare their size to the original marshmallow and guess how much they expanded.

• Use your fingers and observe one of the marshmallows. Is it fluffier or harder than the original marshmallow? (It should be fluffier)

• Allow the other marshmallow sit until it is completely cool, about 10 minutes
• Observe its texture (it should be very hard and crumble when you pick it up)

What’s happening in this experiment?

Marshmallows are made of sugar and water wrapped around air bubbles. When the marshmallows cook in the microwave, the water molecules vibrate very quickly, making the water heat up. The hot water warms the air and the sugar, which softens a little. The gas molecules move around faster and push against the walls of the container. Since the sugar walls are warm and soft, the bubbles expand, and the marshmallow puffs up. If it puffs up too much, the air bubbles will burst, causing the marshmallow to deflate.

When the marshmallow cools, the bubbles shrink and the sugar hardens again. When the microwave marshmallow cools, it’s dry and crunchy. It is more dry than the original marshmallow because some of its water evaporates when it is hot.