What you need:
Four glasses, sugar, food or poster colours, water, straw
What to do:
Pour equal amounts of water into all the glasses. Water that is slightly warm will work better for this experiment.
Add a different colour into each glass. We have used red, blue, green and yellow.
Now, start adding in the sugar. The first glass with the red water has no sugar. The second glass, the blue one, has one whole teaspoon of sugar. The third one (green) has two teaspoons and the fourth one (yellow) has three.
Mix in the sugar until it dissolves completely. Warm water helps the sugar dissolve faster.
Now, dunk one end of the straw into the red water which has no sugar. When you have about 1 cm of the liquid in the straw, cap the other end of the straw with your thumb. Lift the straw out of the glass.
Dunk the straw into the second glass. This time, go in deeper than you went into the first glass. To get the blue water in the straw, lift your thumb from the straw-top but replace it quickly. Repeat this with the remaining two glasses, going in a little deeper each time. But you do need to be quick with your thumb!
What happens?
You get layers of different colours in the straw! Yellow water is at the bottom and red stays at the top.
Why?
When you dissolve sugar into water, you increase the density of the water. Density is nothing but how packed’ the molecules of an object are. Adding sugar molecules into the water, increases the number of molecules in the liquid, thereby increasing its density. So, yellow is the densest solution here, and red is the least dense. As a rule, the less dense liquid floats on top of the one with more density. So, the sugar solutions separate into layers, each with a different density. The topmost one is the least dense and the bottom one has maximum density.
Picture Credit : Google
