DESCRIPTION:
In this demo, food coloring is added to a stirring beaker of water to create a tornado of color. This could be used as an example of a physical change, or to demonstrate the importance of properly mixing solutions.
TOPICS COVERED:
– physical change
MATERIALS NEEDED:
– 1 L beaker
– food coloring
– water
– stir bar
– stirrer
PROCEDURE:
1. Fill the beaker with water (about 800mL), and get stirring on a stir plate.
2. Add a drop of food coloring to the center of the stirring vortex.
ADDITIONAL COMMENTS:
This demo seems to work best if there is a small ( ~1” long and ~1” wide) swirling vortex at the top of the beaker. Use a stir bar that is 1” long, and adjust the speed settings on the stir plate to create a vortex this size. If a light color, like yellow, is used first other colors can be used to repeat the tornado in the same beaker until the water becomes too difficult to see.
SAFETY:
Safety goggles should be worn at all times.