Tuesday, October 21, 2014

Mind Blowing Science: Tug of War

Tug of War is another experiment from Janice Van Cleave's Chemistry for Every Kid

To do it, you need foil, food coloring (red or blue is suggested), rubbing alcohol, water, eyedropper or pipette, 2 cups.
Put water in one cup. Color water with food coloring.
Pour some alcohol in second cup. (Mommy did this part.)
Put some colored water in the center of the foil. ("The thinner the water the better.")

Next, use the pipette to add a drop of alcohol to the center of the colored water.
To see what happens, watch the video.

"The water molecules on the surface of the water are pulling equally in all directions before the alcohol is added. When the drop of alcohol touches the water there is an immediate separation between the two liquids. Alcohol is pulling away from the water and the water is pulling away from the alcohol. The water molecules seem to be victorious and the water spreads outward taking some of the alcohol with it. This outward movement causes the alcohol to be spread into a thin layer over the the foil. It also causes the water molecules to stack up and form a ridge around the alcohol layer. The ridge has a pulsating motion because the water and alcohol molecules continue to pull on each other. The pulling stops when the two liquids totally mix together."

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