The aim of this exciting labour is to observe the effect that yeast has on a sugar solution.
Things Required:
1 package of powdered yeast sugar
Glass
Soda bottle
Measuring spoon-tablespoon (15 ml)
Measuring cup (250 ml)
10-inch (25 cm) balloon
Directions:
Mix the package of yeast and 1 spoon of sugar in one cup of warm water. Be sure the water is warm, not hot. Pour the solution into the soda bottle. Add another cup of warm water to the bottle. Squeeze the air out of the balloon and place it over the mouth of the bottle. Place the bottle in a warm, dark place for 3 to 4 days. Observe the bottle daily.
This Is What Happens:
Bubbles are continuously being formed in the liquid. The balloon is partially inflated.
Science Behind It:
Yeast is a fungus. It has no chlorophyll like other plants and cannot produce its own food. Like animals, yeast can use food such as sugar to produce energy. The yeast causes the sugar to change into alcohol, carbon dioxide and energy. The bubbles observed in this experiment are carbon dioxide. This same gas causes bread to rise during baking as the bubbles push the moist dough up and outward. Gas holes can be seen in the finished bread. The nice smell from the baking of yeast bread is partially due to the evaporation of the alcohol produced.