Your Challenge: Create a fun toy that demonstrates different chemical properties!
Rubbing (isopropyl) alcohol
Tall, clear jar
Food coloring (optional)
- Lay out some newspaper on a table to help contain any mess.
- Fill the jar about 1/4 of the way up with rubbing alcohol.
- Add a couple of drops of food coloring, if you wish.
- Fill the jar the rest of the way with vegetable oil, leaving about a half-inch of air at the top of the jar.
- Add a few trinkets into the jar (glitter, sequins, and other sparkly things look awesome!)
- Add more oil until the jar is filled to the brim.
- Screw the lid of the jar on so that it’s tightened completely.
- Give your jar a shake! Can you mix the oil and alcohol together completely?
How It Works:
The oil and alcohol in your glitter globe remain separate because oil is nonpolar while alcohol is polar. Polar molecules have a slight positive charge at one end of the molecule and a slight negative charge at the other end of the molecule because of how the atoms and electrons are arranged. The electrons in a nonpolar molecule are distributed evenly so there is no difference in charge throughout the molecule. Polar molecules are attracted to other polar molecules while nonpolar molecules are attracted to other nonpolar molecules. However, polar and nonpolar molecules repel each other, which is why the vegetable oil and rubbing alcohol do not mix. Since the alcohol is less dense than oil, the alcohol floats on top of the oil.
- Polar and nonpolar properties play a huge role in the cell membranes that exist in living things!
- Cell membranes are composed of a phospholipid bilayer–phospholipids have a polar “head” and a nonpolar “tail.”
- The cell membrane bilayer is formed so that the polar “heads” are on the outside of the membrane, while the nonpolar “tails” are on the inside.
- This allows small nonpolar substances to easily pass through the membrane, while polar substances need to pass through special channels to enter a cell.