What you need:
A glass, raisins, drinking soda, background music
What to do:
1. Fill the glass with soda.
2. Switch on the music.
3. Drop a few raisins into and watch the show!
What happens?
Initially, the raisins sink into the soda. But then, suddenly, they begin to bob up and down. Depending on the strength of the soda, this could go on for a couple of minutes!
Why?
It’s all a matter of destiny…er… density. As a rule of thumb, if an objects density (i.e. how close its molecules are packed together) is higher than the density of the liquid it is tossed in, the object sinks. If its density is lesser than that of the liquid, it floats.
When the raisins are thrown in, their density is more than the soda’s. So the raisins sink to the bottom of the glass. But the soda water contains carbon dioxide (that’s why cold drinks are also called ‘carbonated’ drinks). The bubbles of carbon dioxide find that the surface of the raisins is rough and uneven. So they attach themselves happily to the raisins. Pretty soon, the raisins are peppered with these bubbles.
Now, these bubbles contain air which is less dense than the soda water. A lot of these bubbles means that there is a lot of air surrounding the raisins. This decreases their density, making them rise up. Once the raisins reach the top of the glass, the bubbles on them begin to pop because the carbon dioxide gas leaves the soda. Without the bubbles, the raisins sink down again. There, they find new bubbles. And it starts all over again until the soda becomes flat or loses most of its carbon-dioxide.
Picture Credit : Google
