Have you ever seen raisins dance the tango or spaghetti noodles do the hula? Follow the directions below to find out how to create your own performing raisins. Believe it or not, you don’t even need music.
Materials: carbonated water or clear carbonated soda, a large clear jar or cup, raisins, popcorn kernels, uncooked spaghetti noodles or rice, food coloring (optional)
To Do:
Pour the carbonated soda into the cup until it is approximately ¾ full.
Drop five to six raisins into the cup. What happens to the raisins?Can you think of a way to make the raisins dance faster? Experiment with different types of carbonated beverages or different sizes of raisins. You can even create your own carbonation by adding a spoonful of baking soda to a glass of vinegar. The baking soda reacts with the vinegar to produce carbon dioxide gas, the same type of gas in carbonated sodas.
Now Try This:
Continue to watch the raisins closely. Do you notice anything forming onthe surface of the raisins?
After a minute or two, the raisins should begin to rise to the surface of the soda. What happens to the raisins when they get to the top of the liquid?
Try adding a few popcorn kernels, grains of rice, or small pieces of uncooked spaghetti (the angel hair variety works best). Do you get the same results? For a more colorful effect, you can add a few drops of food coloring to the cup of soda.
Can you think of a way to make the raisins dance faster? Experiment with different types of carbonated beverages or different sizes of raisins. You can even create your own carbonation by adding a spoonful of baking soda to a glass of vinegar. The baking soda reacts with the vinegar to produce carbon dioxide gas, the same type of gas in carbonated sodas.
What’s Going On?
Raisins are slightly denser than soda, so when you first drop them into the liquid they sink to the bottom. Soon, however, the carbon dioxide gas bubbles in the beverage begin to attach themselves to the rough surfaces of raisins, making them more buoyant. Eventually enough bubbles attach themselves to the raisins that the density of the raisins and the gas bubbles is less than the density of the soda. This causes the raisins to float toward the top of the soda. The bubbles act like tiny life preservers. Just as a life jacket allows a person float in the water, the gas bubbles allow the raisins to float in the soda. When the raisins get to the surface, most of the bubbles burst, causing the raisin to sink back down to the bottom where the process starts all over again.
Debbie DeRoma is the educational specialist for the Reuben H. Fleet Science Center.
