The Unpoppable Balloon Science Trick

In this science activity, you can put a balloon into a candle flame without it popping! How is that possible? It’s all about heat transfer.

A balloon filled with air will pop when it gets too close to a flame as the heat from the candle warms the balloon’s skin and weakens it. The trick to making an unpoppable balloon is to add water to it. The heat from the flame heats the water instead of the balloon, which then doesn’t burst.

If you thought putting a skewer through a balloon was impressive, the unpoppable balloon science trick will blow your mind!

You’ll need

Two balloons

Water

Safety goggles

Candle

Matches

Plate

This activity requires adult supervision.

Unpoppable Balloon Instructions

Put safety goggles on.

Light the candle and place it safely on a plate. A tea light candle works well.

Blow up the first balloon and slowly lower it over the lit candle. The balloon will pop.

Popped balloon as part of an unpoppable balloon STEM challenge

Half blow up the second balloon and add about 200ml of cold water. Blow it up to the same size as the first one.

Lower the balloon over the candle again. The balloon should be able to touch the flame and not pop.

Balloon containing water sat in the flame of a candle

Why does the balloon containing water not pop?

It’s all about heat transfer. When the first balloon moved near the candle, it popped because the heat from the candle weakened the balloon skin, which then burst.

The balloon containing water didn’t pop, as the water absorbed the heat energy from the candle, not the balloon skin. Thanks to the water, the balloon didn’t get hot enough to burn. Water is much better at absorbing heat than air.

The black substance on the bottom of the balloon containing water is carbon from the candle flame.