Purpose
To demonstrate how the gases from yeast can be used to blow up a balloon.
Additional information
Everyone loves balloons! The bright and festive colors cause a feeling of well being in all of us. They make us happy! Of course, the process of actually blowing up the balloons is anything EXCEPT happy! It can be a frustrating task as we try our hardest to blow the balloon up only to have all the air escape as soon as we try to tie it. By the time we're on our 3rd balloon, we're all out of breath and wishing there was an easier way. Using yeast, some sugar, and some warm water we'll do just that!
There are about 1500 species of yeast, which are a growth form of eukaryotic microorganisms classified in the kingdom Fungi. The species of yeast, Saccharomyces cerevisiae (also known as S minor), has been used for thousands of years for baking (such as in breads) and fermenting of alcohol (such as beer). Modern uses of yeast species have been used for generating electricity in microbial fuel cells and producing ethanol, a biofuel.
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Required materials
- 1 Packet of dried yeast
- Teaspoon
- Warm water
- Sugar
- Clear plastic bottle (such as a small empty soda bottle)
- 1 or more balloons
- Large bowl (optional)
Estimated Experiment Time
Approximately 15 minutes
Step-By-Step Procedure
- 1. Pour the packet of dried yeast into the clear plastic bottle
- 2. Add some warm water to the bottle so that the bottle is about 1/4 filled
- 3. Add a teaspoon of sugar to the bottle and swirl the bottle around
- 4. Place the balloon over the mouth of the bottle so that it's fully covered and there are no leaks
- 5. Place the bottle with the balloon on it on a warm windowsill or place it into a large bowl of warm water
Note
Sugar, along with vinegar, produces the best conditions for yeast to ferment.
Observation
What is happening when the bottle is placed in the warm bowl or warm window sill? How do you think the addition of sugar is helping the process? This process is similar to that of baking bread. Can you describe what causes the yeast to rise?
Result
After placing the bottle in the warm bowl of water or on the warm window sill, the balloon will "magically" blow itself up. By adding sugar and warmth to the yeast, the yeast (which is a plant) grows and produces a gas called carbon dioxide. The carbon dioxide trapped inside the bottle rises and fills up the balloon.
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