Friday, March 8, 2013

Milky Rainbows

Concept: Intermolecular Polarity
Intermolecular forces are forces that are exerted by molecules on each other. Such forces may be either attractive or repulsive in nature and may polarize accordingly.

Read Aloud: Naked Eggs and Flying Potatoes by Steve Spangler

Ingredients:
      ·         Whole  Milk
      ·         Food Coloring
      ·         Liquid Dish Soap
      ·         Q-Tips

Demonstration:
      ·         Pour enough whole milk on a plate to completely cover the bottom of the plate. Allow the milk to settle.
      ·         Carefully place 4-6 drops of food coloring on top of the milk. Keep the drops close together but not touching near the middle of the plate.
      ·         Put a drop of liquid dish soap on the end of a Q-Tip. Place the soapy end of the Q-Tip in the center of the plate and hold it there for 10-15 seconds.

Experiment:
·         Will the experiment work if water is used in place of milk?
·         What kind of milk produces the best swirling of color?

Observations:
Food coloring contains water, which is a polar molecule. Milk contains fat, which is a nonpolar molecule. Dish soap, on the other hand, has both polar and nonpolar chemicals in it. The polar chemicals of the dish soap dissolve the water in the food coloring while the nonpolar chemicals of the dish soap dissolve the fat in the milk. As these chemical bonds are weakened, the molecules move in all directions and take the colors along with them.

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