A simple demonstration polar and nonpoloar solutes and solvents may be made using a clear plastic bottle, yellow cooking oil, water, and food coloring. The dye components in many food colorings are polar and would rather stay dissolved in water rather than in nonpolar cooking oil. Therefore one can make a bottle half-filled with oil and half-filled with water and food coloring. When the bottle is shaken the two layers temporarily mix, yielding a different color (ie. yellow and blue combine to make green - a good illustration of color mixing). The bottle cap can be superglued or epoxied to the bottle to keep the contents in the bottle. Bottles of this sort have been used at day care centers for years (special thanks to Karen Campbell for introducing this demonstration to me).
ABOVE LEFT: Bottle with separated layers: oil on top (ferrocene added to enhance the yellow color) and water and blue food coloring on the bottom.
ABOVE MIDDLE: The shaken bottle (note the mixed green color). The separation will return in a few minutes.
ABOVE RIGHT: My daughter playing with the sealed bottle.
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