At the start of the summer, my kids and I sat down to brainstorm fun activities for our “staycation.” We needed a list of creative ideas to fill those idle moments when boredom creeps in and sibling squabbles start brewing (because, let’s be honest, siblings are world-class experts at pestering one another). Out of our brainstorming session came a variety of activities, but one of the most exciting highlights? The Diet Coke and Mentos Geyser experiment.
If you’re unfamiliar with this fascinating experiment, it’s a simple yet thrilling science activity that involves dropping Mentos mints into a bottle of Diet Coke. The reaction causes the soda to erupt in a spectacular geyser, sometimes reaching several feet into the air. This phenomenon occurs because the Mentos disrupt the carbon dioxide in the soda, causing rapid release of gas. Whether this reaction is chemical or physical is still debated among scientists, but you can find more details at one of my favorite kid-friendly science resources, Steve Spangler Science. Notably, diet soda works best for this experiment because it creates a dramatic effect without leaving a sticky residue.
Here’s a detailed guide to creating your own summer fun with the Diet Coke–Mentos Geyser.
What You’ll Need
- A two-liter bottle of Diet Coke (or more, if you’re feeling adventurous).
- A pack of Mentos mints (plan on using one pack per bottle).
- A wide, open outdoor space like your yard or a park field.
- Optional: A camera or phone to capture the action and excitement.
How to Set It Up
Prepare Your Gear: Set your camera or phone to the proper mode beforehand. Trust me, you don’t want to be fiddling with settings as the geyser shoots into the sky! If possible, position it at a safe distance with a wide-angle view. Better yet, record a video for a fun keepsake.
Choose the Perfect Spot: Place the Diet Coke bottle on a flat surface in the middle of your chosen outdoor space. This keeps the area safe from any stray soda splashes. If you have pets, like our overly curious dog, make sure they’re inside during the experiment—Diet Coke seems to attract dogs as strongly as Mentos attract carbon dioxide bubbles!
Load the Mentos: Open the Mentos pack and get them ready. You’ll need to drop all the mints into the bottle at once to achieve maximum fizz and height. Using a rolled piece of paper as a makeshift funnel can help guide the Mentos into the bottle, though we found that simply pouring directly from the pack works just as well.
The Moment of Action
When everything is set, quickly dump all the Mentos into the open bottle of Diet Coke. Be swift—once the first Mentos hits the soda, the reaction begins almost instantly. Step back fast to avoid getting drenched!
If executed properly, the Diet Coke will shoot up in a dramatic geyser that can reach several feet into the air. My kids couldn’t resist trying to catch the soda in cups—or even straight into their mouths! (Pro tip: If soda isn’t a common treat in your house, like in ours, this adds an extra layer of excitement.)
The Pros and Cons of the Geyser Experiment
Pros:
- Kids of all ages are absolutely mesmerized by the explosion.
- For a few glorious minutes, you’ll be crowned the coolest parent ever.
- It’s not just fun—it’s educational! Kids can learn about physical and chemical reactions in a hands-on way.
Cons:
- The excitement lasts for about five minutes, start to finish.
- While it’s thrilling, the activity isn’t the most cost-effective for the time it takes. A couple of bottles of Diet Coke and Mentos will set you back around $7, and the show is over in a flash.
Was It Worth It?
For me, as a parent, the Diet Coke–Mentos Geyser is definitely worth trying at least once. Seeing the pure joy on my kids’ faces and hearing their laughter as they watched the soda shoot skyward made it all worthwhile. My kids’ verdict? An enthusiastic “Yes!”—they’d gladly do it over and over again.
Tips for Making It Even More Fun
- Experiment with Variations: Try using different types of soda to compare the results. Regular cola, flavored sodas, and even sparkling water can produce varying effects, though Diet Coke tends to perform best.
- Take It Up a Notch: If you’re feeling creative, challenge the kids to predict how high the geyser will go or see if they can break their personal record for the tallest soda eruption.
- Capture the Chaos: Don’t forget to document the geyser from different angles. Slow-motion videos are particularly satisfying and make for great memories.
After our geyser adventures, we spent some time discussing what we learned. The kids were fascinated by how something so simple could create such a dramatic reaction. While the activity itself is brief, the excitement and memories linger long after the soda dries on the grass.
So, if you’re looking for an easy, quick, and unforgettable way to inject some fun into your summer, the Diet Coke and Mentos Geyser is a must-try. Just don’t forget to grab a towel—things can get messy!
