Mentos Science Projects

An Internet video showing the effect of dropping Mentos candy into a two-liter bottle of soda grabbed national attention. When Mentos are introduced to a carbonated beverage, the candies' gelatin and gum arabic break the water's surface tension, creating bubbles of carbon dioxide. The dramatic geyser that results from the physical reaction has become a popular demonstration in science projects and experiments.

Mentos and Soda

The basic experiment for creating a carbon dioxide geyser requires a box or roll of Mentos candy, a two-liter bottle of soda, a piece of paper and a piece of cardboard. Place the soda on a flat surface outdoors; you may want to secure it so that it doesn't fall over. Remove the candy from the box or wrapper. Roll the piece of paper into a long tube the width of the candy. Slide the candy into the paper tube in a stack and place the piece of cardboard on the bottom of the tube so that the candy won't fall out. Have a friend open the soda. Position the roll of candy over the bottle with the cardboard against the open bottle top. Instruct everyone to stand back and pull the cardboard out quickly so that all the candy falls into the bottle. Stand back and observe the size of the geyser that follows.

Changing Variables

Use the same basic procedure to experiment with different types of candy and soda. Try diet soda and different flavors of Mentos candy. Change the ratio of candy to soda. Swap out cola for other soda water or juice. Test the experiment with mints, gum or plain sugar. After observing the reactions of each, discuss which variables seem to be the source of the reaction that occurs. Make predictions about which combinations will create a reaction and which will not.

Volcano Project

The basic soda and Mentos experiment can be adapted for use in the classic baking soda and vinegar volcano project. Craft a volcano model using clay, papier-mache or hard-drying foam sealant formed around a tube as wide as a two-liter soda bottle. Once dry, use paint or markers to color the volcano form. Place a two-liter bottle of red soda or clear soda colored with red dye in the center of the volcano. Dropping several pieces of Mentos candy into the soda will cause a lava-colored eruption.