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!

  • Caileigh Sovie

    cant wait to try it but my mom made it really mad

  • Science_Queen_Of_The_Land

    Did This For a science expo project. So many factors effect the results such as weather (temp. and rain/sun), how many mentos, and the soda type. for a way more moderate and less exciting explosion, use Fizzy Water (or fizzy water with cory syrup.)

  • John

    same here

  • jc morgan

    I am doing it for the science fair

  • THAT GUY

    same here, doing it for science project

  • Angel Alexander

    Same here

  • Gibby

    The CO2 would of been mostly released after opening the bottle and the reason for the explosion is mostly from pressure inside the full bottle.
    Good idea though i wished it would work!

  • Harry Styles IS MINE

    I hope this is good more my science project it due in march :D i will give the website Credit :D

  • lala

    i tried this for a science project and with 8 mentos (i am in 5th grade and i did this with out a nozzle) and it only went 19 inches.

  • Elyssa Caldera

    I did it for a project and it worked!!

  • Arthur Kirkland

    Same here, Love.

  • annzbeth

    im a girl

  • Arnaj Singh Sandhu

    really??

  • Arnaj Singh Sandhu

    wow

  • MarkusLiu

    I’m gonna do this for my project. :3

  • MarkusLiu

    me 2

  • Rusty eves

    I am but i have to get the supplys to do it lol……….

  • Rusty eves

    but why does every one have to do it at kalkaska middle school

  • blahgirl

    yeah same!!! I gotta do this for a science project and it better work

  • toxicsandwhich

    SCience experiment is in the works thx eppybird

  • Hezekiah

    Add 20 mentos to a full bottle of coke

  • Floating Ball0

    Did for my science fair!

  • CrazyNerd66

    I have to do it for my Science Expo and it’s due in less than 2 days
    So… hopefully it will work

  • Luis

    I agree this is 4 a science project!!!! So yeah!!!! It better!!!!

  • GAYBOY69WITHBOYS

    IT ALL BANTA REALLY BANTA

  • Mariie ❤️

    What happens if you only put one mentos?’ & What other ingredient might cause the same reaction as the soda & mentos?

  • cala

    thats really cool

  • cala

    oh it will work

  • Kenny Roth

    this experiment was a downer :( it didn’t even worked properly
    ….GAY :)

  • Kenny Roth

    v u suck

  • Saddddddddd

    Ugh the diet coke works but not others!

  • Alyssa

    When was this published?

  • ricky

    why is coke so tall when you put one mentos in coke?

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  • RONZ

    WHERE GONNA DO A EXPERIMENT SO I PICK THIS EXPERIMENT !

  • Blah Bluble Bleah Blahhhhhhh

    Hello This is awesome sauce

  • guest boi

    doing the report for it now

  • Emperor_has_no_clothes

    Hey you shallow kids, how about doing something for science fair that’s a little more original? You’re sacrificing real creativity and learning for a bit of drama.

  • tejas

    Lol same here