Observing gas produced by the combination of sugar and yeast
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SOL: Science:
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Objective:
Materials:
yeast
sugar
warm water
flask or small soda bottle
balloon
1/2 tablespoon measure
1/2 cup measure
Procedure:
Measure 1/2 tablespoon of yeast and pour it into the soda bottle. Measure 1/2 tablespoon of sugar and pour it into the bottle. Measure 1/2 cup warm water and pour it into the bottle. Swirl the bottle so that all of the contents are well mixed. Ask an adult or a friend to hold the bottle while you put your balloon over the mouth of the bottle. Observe your bottle every five minutes.
Ask students to make a prediction about what will happen to the balloon. Do they think the balloon would fill with gas if only yeast and water were in the bottle?
Why?
Yeast is one kind of fungus. Yeast can use sugar as food. Several chemical changes are occurring inside the bottle. The yeast causes the sugar to turn into alcohol, carbon dioxide, and energy. Carbon dioxide fills the balloon. Students may remember that yeast is used in bread baking. Carbon dioxide gas causes the bread to rise during baking as the bubbles push the moist dough up and outward.
http://www.youtube.com/watch?v=AQnmwC69i9s