Super Fun (and Explosive) Soda Pop Geyser Experiment

Kids are natural scientists.  From the moment they are little, sitting in the high chair and dropping their spoon over and over again, they are experimenting and learning.

As they get older it is important to keep that love of science growing, and there is no better way to do it than with fun experiments.

This soda and Mentos experiment is one that your child will beg to do over and over again.  Making a soda pop geyser is one of our favorite STEM activities to do outside.

This soda pop experiment is best done outdoors, preferably in a grassy area.  

You can use either regular cola or diet cola for this experiment.  Diet cola is often chosen because it is less sticky and therefore easier to clean up.  It also has the most explosive reaction.  

The brand doesn’t matter a lot, so feel free to buy a cheaper brand, which is helpful if you want to do the experiment several times.  (Trust me, your kids will want to do it several times.)

Looking for more explosive experiments?  Check out how to make elephant toothpaste.  

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Soda and Mentos Experiment 

Materials Needed: 

• 2-liter bottle of cola
• 1 roll of Mentos mints
• clear tape

To begin the Mentos geyser science project get out 7 of the mints (half the package) and line them up so they are touching each other.  

Pull off just enough tape and secure one side of the mints to the tape.  This will enable you to get all the mints into the cola quickly, while still leaving enough surface area of the mints for the experiment to work.  (You can also buy this special Geyser Tube to help get the Mentos in all at one time.)

Once your mints are ready, position your pop bottle firmly on the ground so it won’t tip over.

Then carefully open the bottle of soda pop.  Try not to shake it, as this will reduce the effects of the experiment.  

Drop the tape holding your mints into the cola and quickly back away.  Watch the amazing soda pop eruption!

Why does the Mentos geyser experiment work?  

Carbon dioxide is pumped into pop bottles at the factory.   This is what causes bubbles to rise to the surface when you first open the soda.

Mentos candies actually have tiny pits all over the surface.  These pits are the perfect place for those little carbon dioxide bubbles from the cola to collect.  

Since the Mentos are heavy, they quickly sink to the bottom of the bottle.  Eventually all those little air bubbles that collect on the candy work to push the cola up and out of the bottle in a dramatic way.

Extensions for the Coke and Mentos Experiment 

Want to take the experiment even further?  

• Have your child guess how high the soda pop will erupt.  Then measure to see how close they are.  Mark distances with sidewalk chalk or tape on an outdoor wall and place your bottle against the wall to see how high it goes.
• Determine whether temperature affects the results.  Try the the soda pop experiment with a cold bottle of soda and a warm bottle.  Does one react better than the other?  
• Experiment to find out which type of soda pop has the biggest reaction with Mentos.  Try cola, diet cola, orange, and a clear soda pop.
• Experiment with the candies used.  Do you get a bigger reaction if you use more Mentos?   What if you use a different flavor?  

Making things explode is definitely one of my son’s favorite types of science experiments.  

Luckily I planned ahead and had enough materials to do the soda and Mentos experiment several times.  It was definitely a huge hit.  

Other kids science experiments you may like:

• How to Create Beautiful Egg Geodes 
• Amazing Rising Water Experiment 
• Ivory Soap Explosion 
• How to Make a Rubber Egg
• Make a Cloud in a Jar

   

You can find this fun experiment and many more in our co-authored book, Up! 

Originally published July 25, 2016