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Balloon on a Skewer

Balloon on a Skewer

Balloon on a Skewer

What do you need?


What do you do?

  1. Blow up your balloon and tie it.
  2. Gently and in a circular motion, push the skewer through the bottom of your balloon (near the knot). To help the skewer in, gently stretch the other end of the balloon while you push the skewer through.
  3. Gently and in a circular motion, keep pushing until the skewer pokes through the top of the balloon.
  4. Has the balloon popped? Don’t worry about it! Just pick up another balloon, and try again. We promise you’ll have a balloon on a skewer soon enough!

What’s the science behind this?

The rubber of the balloon is made up of many long chains of molecules (called polymers), like beads on a string. These polymers are linked through bonds called cross-links, which give them the property of elasticity, meaning they can stretch and then get back to their original shape. What happens when you over-stretch these bonds? Just like in an over-inflated balloon, they break, and the balloon pops!

After inflating the balloon, you’ll see that the areas at the top and the bottom of the balloon are darker than the rest of the balloon. These spots are darker because they’re thicker and less stretched than the rest of the inflated balloon. This is why we can push the skewer through without severing the bonds and popping the balloon. The skewer does break some cross-links, but there are still enough cross-links around the skewer to keep the balloon intact.

What happens if you try to push the skewer through the middle, where the balloon’s rubber is stretched more thinly? The polymers would tear instead of stretch, making the balloon pop.

Sadly, you can’t leave your balloon skewered for long… if you put it aside and wait for a few minutes, you will see the air slowly escaping the balloon through the holes made by the skewer.