Middle School Projects With Mentos & Coke

Made popular by many YouTube videos, a science project that tests the outcome of adding Mentos candy to Diet Coke will certainly have a cool factor for middle school students. This chemistry project is easy, safe and cost effective, with the only downside being the mess. However, performing this experiment outside will greatly reduce the mess factor. Middle school students can learn about controls and variables by testing various sodas and candies to see if the same effects are achieved.

Nucleation

When you drop Mentos candy into a bottle of Diet Coke, a foaming geyser erupts from the bottle. The Diet Coke and Mentos project is a way to teach middle school students about nucleation. When you observe the surface of a Mentos candy it will appear smooth to the naked eye; however, when put under a microscope, you will notice that the surface is filled with divots and craters. These craters serve as a nucleation site when combined with Diet Coke. A nucleation site is a place where a physical reaction occurs. Carbon dioxide bubbles in the soda collect in the craters and divots where they begin to expand and escape from the soda creating a geyser-like effect.

Setting Up

This project will likely excite middle school students. They will want to experiment to see who can get the biggest explosion; therefore it is best if this project be conducted outside on a nice day. This will minimize the mess in the classroom. Teachers should gather materials ahead of time. Determine which sodas and candies you want to test. Middle school students can prepare by hypothesizing which candy and soda combinations will have the biggest effect.

Experiment

Prepare several cups or bottles of Diet Coke. Drop mint or fruit flavored Mentos into the cup or bottle and observe the reactions. A geyser should erupt from the mouth of the bottle or cup, depending on how many candies are added. Geysers can reach as high as 32 feet in the most extreme cases. A 2006 experiment conducted by the Discovery Channel theorized that the reaction occurs when the gum arabic and gelatin in the candies mix with the caffeine, potassium benzoate and aspartame in the diet coke. However, there is no conclusive evidence for why this reaction occurs.

Testing Different Variables

Diet Coke and Mentos are not the only soda and candy products that middle school students can test with this project. Have students experiment with diet and non-diet sodas to see if the reaction differs. ) Diet sodas tend to work best, likely because of artificial sweeteners such as aspartame. Experiment with different candies to see which candies cause the biggest eruption.