For a fun science experiment with kids, you can use the carbon dioxide fizz from soda to make raisins dance. Carbon dioxide gas in soda gives it its fizz.
a can of clear soda
a tall, clear glass
Process: Pour half the soda into the tall glass. The bubbles you see are carbon dioxide gas released from the liquid. Drop 5 raisins into the glass, one by one. Watch the raisins.
Repeat with the other half of soda when the first amount of soda goes flat.
Result: Raisins are denser than the liquid in the soda, so at first they sink to the bottom of the glass. When carbon dioxide bubbles stick to the raisin, the raisin is lifted because of the increase in buoyancy. When the raisin reaches the surface of the liquid, the bubbles pop, and the carbon dioxide gas escapes into the air. This causes the raisin to lose buoyancy and sink again. This rising and sinking dance of the raisins continues until the soda goes flat.
Additionally, the raisins have a rough surface, which is filled with air pockets. These air pockets attract the carbon dioxide gas, creating the little bubbles.
Explanation:Archimedes’ Principle states that the buoyant force exerted on a liquid is equal to the weight of liquid displaced. Since the raisins have a greater volume, they displace more water, causing the liquid to exert stronger buoyant force. The buoyant force of the surrounding liquid is what pushes the raisins to the top. The same scientific principle is at work when a child uses a set of “floaties” at the pool. The volume of the floaties increases the child’s volume, causing the child to float. Deflating the floaties would cause the child to sink because their volume would decrease.