Mentos Geysers

This was my favorite of our Fascinating Science for Kids experiments…although it only lasted about 20 seconds. The boys, Prince Charming, and I were all amazed with what happened when we dropped Mentos into a bottle of diet soda!

I originally found this experiment on Kitchen Pantry Scientist as well as Steve Spangler Science!

Here’s what you’ll need:  a package of Mentos, a 2-liter of diet soda (dark-colored works best), tape, and a piece of construction paper (or this Steve Spangler Geyser Tube). *Tip:  Get the cheapest Diet Soda you can find!*



 1. Cut your piece of construction paper in half. Begin rolling the construction paper as tightly as possible around the Mentos to make a cyclinder. Check to make sure that it is small enough to fit inside the top of your 2-liter bottle. It won’t work correctly unless the cylinder easily fits in the top of your 2-liter.


 2. After you’ve made the cyclinder, unwrap the mentos and place them inside. Hold your hands over the bottom of the cylinder to keep them from falling out.

Or…if you want a sure-fire way to make it work without using the construction paper, you can buy this plastic tube created specifically for this purpose that can be reused over and over again…


 3. Place the 2-liter of Diet Soda in the middle of your yard and remove the lid. Children should stand at least 15 feet away. Have an adult take the cylinder filled with unwrapped-Mentos (still holding the bottom with your hand) and quickly place it in the top of a the bottle. Run back as fast as you can…unless of course, you want a Diet Soda shower!




The cameraman (aka Prince Charming) didn’t stand far back enough to capture just how high the geyser went, but I would venture to guess it was at least 20 feet!


Investigating the bottle afterwards…we were all amazed!


The Science Behind It:

Even scientists are stumped by this phenomenon. But many speculate that when you drop the Mentos into the soda, you break the surface tension. Soda is bottled with carbon dioxide (which makes it fizz). When you drop the Mentos into the bottle, tiny bubbles form around each of the tiny indentations on the Mentos. And because the Mentos are heavy, they sink to the bottom. When all of this gas is released, it pushes all of the soda up at an incredible force!



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  1. This is so cool! I remember doing this in the parking lot of the local hangout, way past closing time, lol.

  2. Totally Awesome! This would be a great one for the summer time! I might just let my kids try to catch the geyser in their mouth and then run in the sprinkler afterward! Thanks for sharing.

  3. Wow! Looks like a fun afternoon of soda soakers. We just came across this post via Pinterest. Great job making science fun and huge thanks for sharing our link!

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