Mentos and Diet Coke Experiment

Materials:

• Mentos mint candy
• Diet cola
• A variety of containers with varying sized opening
• A narrow test tube wide enough to fit the candy [Klutz and others make a delivery contraption that is easier.]
• Logbook

Procedure:

1. Stack the Mentos candies (approx. half a roll) in the test tube.
2. Cover the opening of the test tube with an index card or similar slim, small paper.
3. Invert the test tube, holding the cover in place.
4. Place the soda bottle outside in and area that can get dirty.
5. Open the soda and place the index card over the bottle opening.
6. Pull the index card away swiftly, dropping the candies into the soda. Be prepared: the eruption happens quickly, so back up fast!
7. Observe the eruption—height, trajectory, duration, etc. Record your observations in a logbook.
8. Repeat the process, varying the opening that the soda erupts from. For example, cut the bottle top to increase the diameter an inch or more. Alternatively, dispense the soda into a vase or pitcher. Or, attach plastic piping or tubing to extend the opening’s neck. Be sure to measure the diameters for each eruption.
9. Observe each eruption, recording the details and compare the results.

This experiment can be visually displayed with photos or videos of the event and a graph of the table’s results.

Why?

The Mentos candy gelatin and gum arabic create an energy that breaks the surface tension of the soda. The pits on the candy coating act as conduits for carbon dioxide bubbles that form immediately when the candy hits the soda, increasing its fizziness. When the candy hits the bottom of the bottle, the gas is released and pushes the soda from the bottle up in the air in an amazing eruption!