Have you ever been walking down the street and stepped in a wad of gum, or got up from sitting only to realize that you have gum stuck to your clothes? Sanitation workers experiment with a variety of techniques to remove gum from surfaces. What do you think works best to remove sticky gum?

Instrucciones en Español

Materials

An old shoe
Gum (five or six pieces)
Spoon or dropper
Butter knife
Paper towels
An old toothbrush
Pencil or pen
Paper
Substances that might remove gum, like peanut butter, petroleum jelly, olive oil, vinegar, rubbing alcohol

Instructions

1. Chew a piece of gum until it loses its flavor. Stick the gum to the bottom of an old shoe. Push it on to really get it stuck on there!
2. Repeat with another four or five pieces of gum. Put each piece of gum on a different spot on the bottom of the shoe.
3. Let the gum dry for at least eight hours. Try leaving it to dry overnight while you sleep.
4. Collect the substances you’ll test to see if they can remove the gum.
5. Use a butter knife to smear some peanut butter or petroleum jelly on the gum. Clean the knife with a paper towel before using it to spread another substance.
6. Use a dropper or spoon to put a few drops of vinegar on another gum spot. Rinse the dropper or spoon with water and repeat with rubbing alcohol, olive oil or any other liquids you want to test.
7. Make notes or draw a diagram so you remember which substance you put on each gum spot.
8. Let each substance soak into the gum for five minutes.
9. Use the butter knife to scrape away each gum sample. As you do, try to judge which solvent loosens the gum best. Use the old toothbrush to brush away any small bits of gum that remain.

What's Happening?

Believe it or not, the same type of materials used to make plastics, rubbers and a lot of other sticky products are also in chewing gum. These materials are known as polymers. Polymers are long molecules made up of repeating parts such as groups of carbon and hydrogen atoms. Polymers make gum stretchy and chewy.

Polymers are also hydrophobic, meaning they do not break down in water. That is why you can chew gum without it falling apart in your mouth. Water and water-based materials won’t affect gum very much, so to loosen or dissolve it, other materials are needed! Hydrophobic materials can combine more easily with other hydrophobic materials such as oils and oil-based materials, like olive oil, petroleum jelly and peanut butter. That's why mixing hardened gum with peanut butter (or other oil) can help you break the gum apart from a hard surface.