Question: Is it true that the cavities in a mentos is what makes the coke fizz?

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  1. Yes.

    Coke is mostly sugar and carbon dioxide dissolved in water. When you put something into it some of the carbon dioxide comes out of solution and forms gas bubbles around the object. This is called nucleation. The structure of the outside of a mentos is rough and the right ‘shape’ to provides a lot of surface points for nucleation to occur.

    Mentos seem to be well tuned to nucleating carbon dioxide out of diet coke, but you should be able to see a smaller version of the same effect occurring if you add other crystal structured materials like sugar or salt. Nucleation is the same effect that causes small water bubbles to gather near you finger when you put it in a glass of water.


  2. Sounds like an awesome idea for an experiment! Maybe you could take some of Lee’s suggestions and try it out yourself 🙂


  3. coke + mentos is a cool experiment. Soft drinks like Coke are a full of dissolved carbon dioxide. That hissing sound you hear when you open a bottle/can of soft drink is the dissolved gas escaping when the pressure drops. The dissolved gas is also what causes all the bubbles that make that nice sensation on your tongue when you drink it. Turns out that the rough surface of the Mentos is just right to let lots of bubbles to form really quickly.