Wikijunior:Big Book of Fun Science Experiments/Rainbow columns
- food colouring
WHAT TO DO
- Take 2 large spoonfuls of salt and dissolve them in 100mls of water.
- Add a few drops of green food colouring.
- Then you take another large spoonful of salt and dissolve it in 100mls of water.
- Then add a few drops of yellow food colouring (if you don't have yellow use any other colour).
- Then add a small spoonful of salt and dissolve it in 100mls of water.
- add some red food colouring to that.
- add a bit of food colouring to a test tube.
- then add another colour of food coloring very very gently.
- add different types of food colouring 2 more times very gently.
- if it mixes together start again and keep on trying till you get a rainbow.
The principle of this experiment is density. Density is the ratio between volume and mass. When different substances of different densities are added to a container, one frequently floats on top of the other because it has lower density. The perfect example of this is oil on top of gasoline.