Coke & Mentos Project Ideas

Some experiments offer students an exciting way to see several scientific principles at the same time. Coke and Mentos projects offer an example of this phenomenon, demonstrating both a chemical and physical reaction. These projects can be fun, but if you're using one as a science project, always include the reasons for the reaction and the physical result.

Volcano

Using a 2-liter bottle of Coke and a couple of Mentos, you can create a mini volcano. The basic experiment involves dropping a couple of Mentos into an open Coke bottle. This will cause a small-scale eruption. For more dramatic results, make your project more complex.

Geyser

The geyser is an extreme version of the volcano and should only be carried out outdoors. Drop an entire unwrapped tube of Mentos into a bottle of Coke. This demonstrates the pressure build-up in the bottle much more vividly than the volcano, as the power of the reaction increases the more Mentos you use. You should see a 10-foot-high plume.

Rocket

This classic experiment using Coke and Mentos demonstrates how an increase in carbon dioxide causes rapidly increasing pressure and, eventually, thrust. Put an entire tube of Mentos still wrapped in the foil, but not the paper, in a 2-liter bottle of soda. Screw on the cap and shake the bottle to stimulate the reaction. Slightly loosen the cap until you hear a hissing. Throw the bottle down on the ground to dislodge the cap and the rocket will take off using the carbon dioxide as a kind of jet fuel.

As a Science Project

These are legitimate science projects, but remember to give your experiment some credence. Try using papier-mch or modelling clay to create a volcano shape around the bottle, or use the geyser or rocket to give a practical demonstration of pressure build-up. The physics behind the rocket's action is actually quite similar to that of a jet engine, by which pressure build-up is used for thrust. Create extreme versions of this experiment using a chain reaction or even multiple bottles.