In first class, we did an experiment called ‘Dancing Raisins’
We put some 7Up into a plastic cup. Then we put in some raisins. They sank to the bottom of the jars and then floated up and down. It was cool.
This is the science behind it;
Raisins are denser than the liquid in the 7Up, so initially they sink to the bottom of the glass. The 7Up drink releases carbon dioxide bubbles. When these bubbles stick to the rough surface of a raisin, the raisin is lifted because of the increase in buoyancy. When the raisin reaches the surface, the bubbles pop, and the carbon dioxide gas escapes into the air. This causes the raisin to lose buoyancy and sink. This rising and sinking of the raisins continues until most of the carbon dioxide has escaped, and the 7Up goes flat. Furthermore, with time the raisin gets soggy and becomes too heavy to rise to the surface.
