Colorful Density Tower in a Glass!

Project Overview: Layer five different household liquids on top of each other in a single glass to build a rainbow tower where each liquid floats perfectly on the one below it, without mixing! This experiment lets you see and explore why some liquids sink and others float on top of each other, and it also doubles as a cool science-themed decoration once you're done. Make sure you pour slowly and carefully, since rushing this step is the most common reason the layers mix together!

Materials:

1. 1 Tall, Clear Glass or Cylinder

2. 1/4 Cup Honey

3. 1/4 Cup Corn Syrup (you can dye it with food coloring, but it is optional)

4. 1/4 Cup Dish Soap

5. 1/4 Cup Water (you can dye it with food coloring, but it is optional)

6. 1/4 Cup Vegetable Oil

7. 1/4 Cup Rubbing Alcohol (you can dye it with food coloring, but it is optional)

8. A Turkey Baster, Pipette, or Small Spoon (to ensure a slow pour)

Instructions:

1. Pour the honey into the bottom of your tall glass first, making sure it spreads evenly across the base

2. Very slowly and carefully, pour the corn syrup down the inside wall of the glass so it lands gently on top of the honey without mixing into it

3. Pour the dish soap down the inside wall on top of the corn syrup layer

4. Slowly pour the colored water on top of the dish soap layer, again pouring down the side of the glass

5. Slowly pour the vegetable oil down the side of the glass on top of the water layer

6. Finally, use the turkey baster or a spoon to very gently drip the rubbing alcohol on top of the oil layer

7. Observe your finished density tower of five distinct and colorful layers

8. Try gently dropping a small object, like a grape, mini rubber duck, a bead, or a coin, into the tower and observe which layer it stops at

Explanation: 

Wondering why some liquids sit on top of each other, other sinks below, and none mix together? This is due to density! Density measures how much mass (weight or matter) is packed into a given amount of volume, or the space it takes up. In short, it measures how heavy something is for its size! However, density doesn't just apply to liquids, it also applies to gases and solids! In our case, we dealt with liquids, and honey was the most dense substance we had, while rubbing alcohol was the least dense liquid. Honey settles at the very bottom, while rubbing alcohol is the least dense, so it floats on top, and the other liquids arrange themselves in order between those two extremes. This justifies that less dense substances rest above denser substances. As long as you pour slowly down the side of the glass, each new liquid gently rests on top of the one below it instead of mixing, which is why the layers stay separated into a colorful stack. This same density-based layering is the reason oil floats on water and why some materials sink or float in liquids depending on their differing densities!