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Rainbow Mentos & Soda Geyser

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Have you ever tried the Mentos and Soda Geyser?  It’s such a fun classic. We did  it years ago with diet Coke. This seems to be the most popular choice of sodas to do the experiment with. But I wanted to do a more colorful version this time. So instead we did a Rainbow Soda and Mentos Geyser!

Of course, my kids LOVED it!!  We had cousins in town for a large portion of the summer so we spent lots of time trying to keep them all happy.  This was a perfect outdoor activity for a busy group of kids.

How to Make a Mentos & Soda Geyser

This little experiment is fun, messy, but over before you know it. Make sure to do this outside!!
(As you can see there will be an array of emotions each time depending on how well they got their mentos into the bottle!)
To do this you just need a 2 liter bottle of Diet Coke (generic brand works just as well), or a whole bunch of colors of soda, I bought all the colors of Fanta, plus some blue & green Mountain Dew.  You need a roll of mint Mentos for each bottle.  And finally you’ll also want a piece of paper to roll the mints in before dropping them in the bottle.
Just roll the Mentos up inside a half sheet of paper- roll them really tight so it will fit through the hole in the bottle. Drop them in all at once & take a step back!  Or, if you are like these kids, drink it as it spouts up like a fountain! 🙂
It seems that Mountain Dew is the lest effective. Diet Coke tends to spray a bit higher, in general, but I think the colorful soda is way more fun!
We did it two times because it was over so fast & it took a time to get the hang of it. Dropping in the Mentos can be a little bit tricky. If you drop one or two in, but not the whole roll, it will be very anti-climactic.
We tried to capture photos and video, but only got a few photos.  Watch the video if you want to see all of it!

The Science Behind the Soda Geyser

How does this work?

Soda is carbonated with carbon dioxide or CO2.  Mentos candies have a porous outer shell. The little openings in the shell make it the perfect place for all of the bubbles in the soda to rest. The bubbles from the soda form all over the candies, pushing all of the bubbles up to the surface and causing the eruption.  Go deeper with the science over at Steve Spangler Science.


Turn it Into a Science Fair Project

You could have a lot of fun turning this into a science fair project by testing which sodas work best! Test several types and brands of soda to see which one shoots the highest.

This is our original try years ago.  I love my son’s expression in the picture!

See More Exploding Science:

Easy Bottle Rockets

Film Canister Rockets


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