Chemistry Experiments You Can Do at Home

Introduction

How can I inflate a balloon using yeast?

  • Biochemical/enzymatic reactions
  • Gases
  • Yeast (5-10 grams powder yeast)
  • A small plastic bottle (preferably about 16 oz. or smaller)
  • One teaspoon of sugar
  • A balloon
  • Warm water
  1. Add enough water to a small plastic bottle to fill it up about 1 inch. The water needs to be warm for the yeast to do its job.
  2. Add about 5-10 grams of yeast (one small packet will do) to the bottle, and mix it around well. Yeast is made of fungal microorganisms that will become active when placed in the warm water.
  3. Add a teaspoon of sugar to the water. The sugar serves as the food for the yeast microorganisms. They are going to consume it and produce carbon dioxide gas as a byproduct.
  4. Wrap the balloon around the open end of the bottle. You may wish to use tape or a tight rubber band to prevent gas from escaping. Let the yeast do their job for about 20 minutes, and the yeast should soon produce enough carbon dioxide gas to start filling up the balloon. This is the same thing that happens when you use yeast to bake bread! The little holes you see in the bread are from the yeast releasing carbon dioxide as it rises.
  5. Try repeating the experiment using different amounts of water, sugar, and yeast, and observe the rate at which the balloon inflates. One hypothesis you might test is whether the concentration of sugar in the water affects the rate of carbon dioxide product. You might also try varying the amount of yeast you use. Pay attention to both the rate at which the balloon inflates, and the final volume of gas it reaches.