Rainbow in a jar- density column

Sometimes the simplest things are the funniest. This demonstration shows multicolored layers in a jar without using much "chemistry". The final result is called "density column" because it allow us to make a pile with liquids with different densities, like we saw here.

In this project we are going to use sugar solutions with different concentrations. Those will form layers, the less dense (more diluted) at the top, the most dense (concentrated) at the bottom of the glass

We will need:

• sugar,
• water,
• food coloring,
• tablespoon,
• 5 transparent plastic cups, you can use flasks or glass cups but they must be transparent.

How to:

• Align the 5 cups on the table;
• Add 1 tablespoon of sugar in the first glass, 2 on the second, 3 on the  third... and so on, leave the fifth empty for now;
• Add 3 water tablespoons (about 45 ml) to the first 4 cups;
• Mix, homogenize the solution, if the sugar does not dissolve completely in any of the glasses add another tablespoon of water to all the glasses,
• Add 2-3 drops of red food coloring first glass, use yellow on the second, green on the third, and blue on the fourth;
• Mix again;
• Now let’s set up our rainbow. First the denser solution (more concentrated), in this demonstration is the blue with 4 sugar tablespoons. Fill 1/4 of the fifth glass with the blue solution;
• Carefully place the green solution on top of blue. The best way to do this is to put the tablespoon inside the glass, without touching the blue solution, and allow the green solution to flow along the spoon;   
• Repeat the procedure to all the solution in this order: Blue (done), Green (done), Yellow and Red. Each solution must occupy 1/4 of the glass.

Note:
If you don't succeed at the first try don't quit, try again. It’s hard to do it right without training.
There is no problem if you drink it, its only sugar water.

To make this demonstration a experiment try:

• To use flavored food coloring, what happens?
• To use water with different temperatures? Does this have any influence in the experience? How? Be careful with burns.
•  What happens if we disturb the equilibrium of the layers? try to use a toothpick and touch 2 or more layers with it.

Et Voilá!
Multicolored drinks, like witch potions.

Enjoy!