PURPOSE: This demo demonstrates diffusion by using food coloring and water.

DESCRIPTION: A drop of food coloring is placed gently into a beaker of water. In a few minutes the food coloring will diffuse through the entire beaker of water. It might be argued that residual currents in the water account for much of this " diffusion." Maybe so, but it gets the point across even if you mention this.

SUGGESTIONS:

EQUIPMENT: Beaker of water, food coloring.

SETUP TIME: 15 min.

KEYWORDS: diffusion