Dropping Mentos candies into Diet Coke causes a rapid release of dissolved carbon dioxide, creating a dramatic soda eruption. This is a physical reaction caused by surface roughness on the Mentos that accelerates bubble formation.

1. Prepare a Mentos cartridge by rolling an index card into a tube slightly larger than the candies and taping it closed.
2. Choose an outdoor location at least two meters away from buildings and overhead obstructions.
3. Place a two-liter Diet Coke bottle upright and stable.
4. Remove the cap and cover the opening with a flat index card.
5. Load four whole Mentos into the cartridge.
6. Place the cartridge above the bottle, aligning it with the opening.
7. Put on eye protection and quickly pull out the flat card so the Mentos drop into the bottle. Step back immediately.
8. Observe the eruption’s speed, height, and duration.
9. For comparison, crush four Mentos into small pieces and load them into a new cartridge.
10. Repeat the procedure with a fresh bottle of Diet Coke, this time releasing the crushed Mentos.
11. Compare the eruptions between whole and crushed Mentos in terms of height and how much liquid remains.

Coke and Mentos Experiment - Emily's Science Lab - Emily Calandrelli:

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📄 Erupting Diet Coke® with Mentos® - Science Buddies: https://www.sciencebuddies.org/stem-activities/diet-coke-mentos

• Test different types of carbonated beverages (regular soda, seltzer, or flavored sparkling water).
• Try different candies with rough or smooth surfaces to compare effects.
• Repeat the experiment with warm versus cold soda to see how temperature changes the eruption.
• Use a measuring tape on a nearby wall to record eruption heights more precisely.

• Safety goggles are required to protect eyes from splashing soda.
• Perform outdoors to avoid mess and potential damage to property.
• Stand back immediately after dropping in the Mentos to avoid contact with the eruption.
• Use caution when cutting or crushing Mentos—adult supervision is recommended.

• Why does this reaction happen so quickly? (The rough surface of Mentos breaks bonds between dissolved carbon dioxide and water, releasing gas rapidly.)
• Which gives a bigger eruption, whole or crushed Mentos? (Whole Mentos sink faster, releasing gas more quickly and producing a larger eruption.)
• How does temperature affect the eruption? (Warmer soda holds less dissolved gas, so eruptions may be larger than with cold soda.)
• What type of soda produces the tallest eruption? (Diet sodas often produce higher geysers because they contain fewer sugars, reducing stickiness and allowing bubbles to rise more freely.)