Amy Sass

The Peanut Race:

Science Concept: Certain chemicals weaken the bonds in a polymer. Polarity vs. non-polarity in an object.

Materials:

2 - 400 ml beakers

30 ml of acetone

30 ml of water

Polystryene foam (packing peanuts)

Starch based packing peanuts

Directions:

1. Fill one beaker with 30 ml of acetone

2. Fill the other beaker with 30 ml of water

3. Put the a few polystryene peanuts into each beaker watch what happens

4. Put a few starch based packing peanuts into each beaker, watch what happens

5. Allow starch based packing peanuts to sit in water for the remainder of the demo show, observe what happens

Introduction:

Place starch based packing peanuts into a beaker filled with water. Pretend that the experiment did not work, leave the beaker sitting there. You know what boys and girls, I am sure tired of doing all these experiments arenít you? Well I am going to play a game? I need two volunteers. (Pick two students). OK, each of you have a beaker with a colorless liquid in front of you, and a bag full of packing peanuts. You each have the same number of packing peanuts. The first person to get all their peanuts into the beaker wins. Ready, get set, go..... (Play game) During explanation show students that the starch based peanuts will not even dissolve in water.

Explanation:

Well these packing peanuts that come in the mail, are actually made up of styrofoam. These peanuts, like everything else in the world are made up of atoms. Carbon atoms are the building blocks of life. Atoms join together to form molecules. These molecules have either a negative or a positive charge. When we say that a molecule is non-polar it means that it does not have a charge, it is neutral. When a molecule is polar it means that it has both positive and negative charge. Only polar molecules dissolve polar molecules, and only non-polar molecules dissolve only non-polar molecules. LIKE DISSOLVES LIKE. The styrofoam is a non-polar substance, it does not have a charge. In one beaker there is water, which is polar (they have both positive and negative charges). The styrofoam will not dissolve because it is non-polar, polar and non-polar do not mix. However, in the other beaker I have acetone. Acetone is what girls use to take off their nail polish. Acetone is a non-polar substance, just like the styrofoam peanuts, so this means that LIKE DISSOLVES LIKE, and the peanuts will dissolve. This is why the one student was able to fit the more peanuts. If you look at the peanuts in the beaker from the beginning of the experiment, they have shrunk. These peanuts are starch based and it is polar, so it will dissolve in water, which is also polar, it just takes longer. These starch based peanuts are more popular now, then the styrofoam based peanuts because they are biodegradable. It is better for the environment because they will dissolve in water, whereas the styrofoam peanuts will not.

Safety Precautions:

Wear goggles
Do not ingest any acetone

Waste Disposal:

Throw out any and all packing peanuts

Put liquids down the drain

Wash beakers out thoroughly

Reference:

Lisa Sammarco, Dr. Ophardt, Science Demonstrations, 2001.