Yeast is a living organism, often used in baking. As you may know, it “breathes” once it is activated my warm water and sugar. Then, it is incorporated into the batter. When baked, the batter gives you soft, fluffy bread or cakes. The yeast gave the bread and cakes the air bubbles, making them soft and pillowy.
In this activity, you can see yeast in action and how it can inflate a balloon and make it explode.
What you need:
• A small balloon
• A packet of regular yeast
• A teaspoon of sugar
• A clean 16-ounce plastic soda bottle
• Warm water
How to do it:
- Get the plastic soda bottle and pour in some warm water filling about an inch high. (Yeast rests when it is cold.)
- Add in the contents of the yeast packet.
- Swirl the water in the bottle for a few seconds. Watch the yeast dissolve and activate.
- Add the sugar and swirl it again. This is when the yeast starts to eat.
- Get your balloon and blow it up a bit to stretch it.
- Fit the neck of the balloon over the mouth and neck of the bottle.
- Secure the balloon’s attachment with some tape.
- Place the bottle in a warm spot in the kitchen for about 20 minutes.
- Watch the balloon inflate.
The moment the yeast consumes the sugar, it gives off a gas by-product called carbon dioxide. This gas fills the bottle and then makes its way inside the balloon. If you examine a piece of bread, you will notice small holes in it. Those holes were produced by the carbon dioxide from the yeast as the temperature increases in the oven. Then, the yeast dies, leaving the carbon dioxide bubbles behind.
In this project, the yeast keeps producing carbon dioxide, making the balloon bigger and bigger. Note the temperature of the room, the size of the container, and the type of sugar you used.