Materials Required:
l Red and blue food colouring
l ½ cup water
l Bowl
l 1 heaping cup cornstarch
l 2 marbles
Procedure:
- Add a drop of red and a drop of blue food colouring to ½ cup of water. Pour this into a bowl. Add the cornstarch and mix well.
- Pick up a handful of this goo and roll it quickly between your hands, forming a ball. The solution feels dry. Stop the rolling action, and the substance loses its form, oozing between your fingers.
This experiment is a good stunt to show your friends—they’ll be amazed!
Press 2 marbles into your purple concoction, and it will look like you’ve made a new kind of creature!
This Is What Happens:
Cornstarch does not form a true solution with water. Instead, solid particles are held up by the water, creating a mixture called a suspension. When you roll the mixture in your hands, you keep the suspension together by squeezing it on all sides. But as soon as you remove this support, the fluid and its particles are able to flow freely, drifting apart. If you let some of the goo sit for several minutes in a clear glass, you will see the cornstarch and water separate into two layers.
