You know yeast as an ingredient in baking bread and pizza. Once it is mixed with water and sugar, it forms bubbles in the liquid. That is because the yeast has just been activated. It produces gas. In this project, you will harness that gas and use it to fill a balloon.

What you need:

• A balloon (small)
• A packet of ordinary baking yeast
• A teaspoon of sugar
• A 16-ounce clear, clean plastic bottle or smaller
• Warm water

How you do it:

  1. Place about an inch of warm water in the plastic water. (Take note that yeast rests when it is dry or cold.)
  2. Open the packet of yeast into the bottle and swirl it for a bit. (When yeast dissolves, it starts to come back to life.)
  3. Add in the sugar and then swirl the mixture again. (Yeasts eat the sugar for energy. Your yeast is not active and eating.)
  4. Take the balloon and inflate it with your breath just to stretch it a bit.
  5. Surround the neck of the bottle with the lips of the balloon.
  6. Place the bottle in a warm corner for twenty minutes. With the right conditions, the balloon will inflate.

How it works:

Yeast forms carbon dioxide when it eats sugar in a warm environment. This gaseous by-product fills the bottle. It travels upward to fill any space available, including the space inside the balloon.

Bread has holes in it, right? These holes are made by yeast, which is a collection of microorganisms that breathe out carbon dioxide in the flour dough as it proofs. As carbon dioxide builds up, the flour increased in size. Yeast creates air pockets inside the dough before it bakes to become bread. The yeast here is related to the Saccharomyces cervisiae strain. The moment the yeast subjected to the heat of the oven, it dies. The air pockets are left in the bread. Because of them, you can enjoy soft and fluffy bread.

You can produce a number of experiments from this project. Use them to
determine the following:

• The room or water temperature that produces the most gas
• How the temperature affects the amount of carbon dioxide produced by the yeast
• If the container’s size influences the amount of gas the yeast produces
• The kind of sugar that helps yeast produce the highest amount of gas


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