Steps in the Mentos in Pop Experiment

The Mentos and diet cola display gained popularity as a viral internet video in the early 2000s. Often it was set to music, as a pair would walk along a display dropping Mentos candies into 2-liter bottles of diet cola. The gum arabic of the Mentos coating reacts with sodium benzoate and the artificial sweetener aspartame in the soda to produce carbon dioxide bubbles, which in turn produce more bubbles.

Setting Up

The first step in the experiment is to place the bottles on a table or stand. They must be fairly close to each other so that you can reach a few bottles as a previous bottle is spewing soda. Bottles in a second row are often angled slightly toward each other to give the illusion of a crossing pattern in the background. Space the rows close enough together that you can reach them both from a position in between them. Once the bottles are in place, unscrew the tops. Do not wait too long to begin the show; as the soda loses its carbonation, it will not be as effective. Diet Coke is the preferred beverage for this experiment because it has higher levels of potassium benzoate, aspartame and carbon dioxide than most other sodas.

Timing Practice

Once the bottles are set up, take a few practice walk-throughs to get your timing down. Practice walking by and dropping a nickel in each bottle without slowing down. Have someone else begin at the other end and walk toward each other. Develop a routine and synchronize your movements. It takes about one to two seconds for the soda to erupt.

The Reaction

When you are ready to begin, prepare your supply of Mentos. Only the original flavor will work; fruit flavors have different ingredients that will not cause the same reaction. As the candy falls, the displacement gives rise to bubbles. The coating used in Mentos contains gum arabic, an ingredient that reduces the already low surface tension of Diet Coke. Crushed Mentos do not work as well, since they will not fall as far into the bottle, and the gum arabic isn't found in the center of the candy---only the dimply coating produces the necessary reaction. The rapid rate of formation of carbon dioxide bubbles is due to the disruption of the polar bonds between water molecules.

Prepare to get soaked as you walk through the set up---the columns of Diet Coke can shoot upwards of 20 feet in the air.