Watch raisins dance and tumble in a glass of soda water.
- soda water (or soft drink)
- small glass
- fill small glass with soda water
- add a couple of raisins to the glass of soda water
Observation and Results:
- what did you observe?
- do the raisins sink or float?
- can you explain what is happening and why?
- can you find other things that dance in soda water?
When raisins are added to the soda water, they sink because of their weight. At the bottom of the glass, the bubbles (carbon dioxide) from the soda water attach to the raisins. When enough bubbles attach to a raisin, it will rise up (like a life jacket for the raisin). When the bubbles detach from the raisin, the weight of the raisin causes it to fall back to the bottom of the glass. This will repeat until there is no longer enough bubbles in the soda water to raise the raisins. This experiment shows that an increase in volume of the raisin from the added bubbles will lead to a decrease in density and therefore the raisin floats in a liquid that normally it would sink in.
Another way to do this experiment is to generate the carbon dioxide gas using the reaction of baking soda and vinegar. Fill your glass about 1/2 full with water. Add one teaspoon of baking soda and stir until it is dissolved in the water. Add a couple of raisins to the glass. SLOWLY pour in vinegar until the glass is about 3/4 full. The vinegar and baking soda react to form carbon dioxide bubbles, and the raisins will dance just as in the soda water!