The Science of Coke and Mentos

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Diet Coke and Mentos - Image by Darren Slover -Sun Journal

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How Does This Work?
Why do Diet Coke & Mentos and Coke Zero & Mentos create such exciting geysers?

It’s mostly due to a process called nucleation, where the carbon dioxide in the soda is attracted to the Mentos (they are awfully cute). That creates so much pressure that the soda goes flying. We then built nozzles that make the opening smaller and that makes the geysers go even higher.

So what is nucleation about and why do Mentos release all this pressure so spectacularly? Read on…

Making Lots of Bubbles
After a lot of debate, scientists are now saying that the primary cause of Coke & Mentos geysers is a physical reaction, not a chemical reaction. Their explanation is this process called nucleation.

All the carbon dioxide in the soda – all that fizz – is squeezed into the liquid and looking for a way out. It’s drawn to any tiny bumps that it can grab onto. Those tiny bumps are called nucleation sites: places the gas can grab onto and start forming bubbles.

Nucleation sites can be scratches on a glass, the ridges of your finger, or even specks of dust – anywhere that there is a high surface area in a very small volume.

The surface of a Mentos is sprayed with over 40 microscopic layers of liquid sugar. That makes it not only sweet but also covered with lots and lots of nucleation sites.

In other words, there are so many microscopic nooks and crannies on the surface of a Mentos that an incredible number of bubbles will form around the Mentos when you drop it into a bottle of soda.

Since the Mentos are also heavy enough to sink, they react with the soda all the way to the bottom. The escaping bubbles quickly turn into a raging foam, and the pressure builds dramatically.

All that pressure has got to go somewhere, and before you know it, you've got a big geyser happening!

Try This at Home!
This is a great thing to try yourself – if you’re careful. Here’s how. Make sure you wear your goggles and lab coats, so that you are not only protected, you also look cool as you run away from the flying soda.

The Big Question
What happens if you drink soda and then eat Mentos? Well, a lot of the fizz goes away as you drink. Then when bubbles are released in your stomach, your stomach can expand a bit. And your stomach also has ways of, umm, releasing excess gas… The MythBusters showed that your stomach won’t explode, but it still wouldn’t be a lot of fun. Do not, repeat, do not be stupid and test the limits of your stomach. Don't even think about it.

What Else Works?
We've tested everything from Mountain Dew & Lifesavers to Moxie & M&M's. Shockingly enough, dropping just about anything into just about any kind of soda creates at least a little fizz. Even some pocket change made a bottle of root beer bubble up a bit. But the combination of Coke Zero & Mentos is particularly potent!

Does It Have to be Diet?
Diet Coke and Coke Zero tend to go a bit higher than regular soda, because they have a little more carbonation and the sweeteners help make the reaction a little bigger. Most importantly, Coke Zero and Diet Coke aren’t sugary and sticky. Every time we set off a big geyser display, we get soaked to the skin, so it’s nice not to get covered in sugary goo.

Interesting Links
Thanks to Tonya Coffey at Appalachian State University in North Carolina for publishing a scientific study of Coke & Mentos in the American Journal of Physics. New Scientist has this great summary of the explanation.

Fun with Nucleation
You can learn more about nucleation sites in action if you coat the inside of a small glass with vegetable oil. Move the glass around to get a nice smooth coating of oil and then pour in some soda. What happens? No fizz. Why? No nucleation sites. Now sprinkle in some granulated sugar. What happens? Lots of fizz! Why? Lots of nucleation sites!

  • flying bird and crash

    100 Mentos in cola lol

  • Butt dude

    Woah I really need this

  • Always Alone

    this project is fun and quite interesting but it is for third grade and lower, at least that’s my opinion

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  • Michael

    Did this for a science fair project for school and this site really helped with the display boars

  • Taylor Willard

    same here selenagomez878

  • herobrine

    doing for science fair

  • herobrine

    lol me too

  • herobrine

    same here science

  • Ffft


  • Ffft

    Join the discussion……

  • Ffft

    3 years ago wow

  • kid2

    i have this as a science project

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  • lolmaster1212

    LOL IT WORKET !!!!!!!!!!!!!! :))))))))))))

  • Queen Sherbert

    Same Im doing a science project as well

  • 123478

    do this it works and it workd 4 science projects :)

  • Cole Patenaude

    Yeah this better work because I have to do this for a science fair!!

  • ari bendavid

    whats up boysssssssssssasssssss

  • ari bendavid

    I like science

  • ari bendavid

    I’m going to harvard in fourth grade

  • ari bendavid

    cool, as well as i am!

  • ari bendavid

    sal lilil

  • ari bendavid

    I’m mad trippin


    Me TOO!!!

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  • melissa

    A friend of mine did that thingy. :lol:

  • melissa


  • melissa

    owwwwwwwwwwwww it hurts

  • Irvin Grijalva


  • sara

    im doing one too

  • sara

    im a boy btw

  • Tori

    For the science fair, I have decided to do different sodas and mentos. I did the experiment first, now my teacher tells me to do research, this website has helped so much!-Thanks

  • britney love

    im doing this for a project

  • sammy

    i am reserching for a science fair project and i have found alot of good information from this website

  • pepe

    ss project i doing this for

  • arabella


  • Vince Britos

    So many commoners………….Same -__-

  • me

    Try taping the soda bottle to a state board and letting it loose down a hill….. :D

  • Dillon Coakley

    enda are you there

  • Enda

    yo dawg turn up

  • Dillon

    sup enda how ya doing

  • Enda

    Im doin good

  • Enda


  • Dillon

    sup DILL

  • Dillon


  • Dillon

    enda you are so good at agar

  • patricia

    i do too