Snack Turns Into a Volcano!? Unleashing the Science of Eruption with Mentos and Coke!
Hi, I’m Ken Kuwako, your Science Trainer. Every day is an experiment!
When we hear “volcanic eruption,” it often sounds like something from a distant world. But guess what? We can safely recreate a mini version of it using everyday items! For this experiment, we’ll be using Mentos and Coke—a classic snack time duo that quickly transforms into a star of science. Why does this violent reaction happen when these two meet? And how is it connected to a real-life volcano?
Let’s embark on a journey to uncover the secrets of the little big eruption right on your desk!
Super Simple Setup!
For this preliminary experiment, the only things you need are:
A 300ml bottle of Coke
One Mentos candy
That’s it! With just these items, you can create a miniature volcano right on your table. We opted for the small 300ml bottle because it’s key to “safe observation.” The smaller volume makes the force and amount of the eruption relatively easy to control, allowing us to closely observe the phenomenon indoors. (P.S. If you want to try 500ml or 1.5L, make sure to do it outdoors in a wide-open area!)
Mentos: The Volcano Switch! The Eruption Mechanism
As the Mentos sinks to the bottom of the Coke, it continuously generates bubbles along its path. This process—”energy (bubbles) rising consecutively from below and pushing up the liquid”—is very similar to how magma, accompanied by gas, rises from an underground magma chamber in a real volcano.
Coke contains a gas called “Carbon Dioxide (CO2)” which is forced to dissolve into the liquid under high pressure. This state is exactly like how water vapor (H2O) and other gases are dissolved in magma under the immense pressure deep within the earth’s magma chamber. Normally, the gas stays quietly dissolved, but given a trigger, it tries to escape all at once.
And the object that provides that “trigger” is the “Mentos”! If you look closely at the surface of a Mentos (a magnifying glass works great!), you’ll find that it’s not actually smooth. It has countless tiny, invisible bumps and irregularities. These irregularities become the perfect “anchor points” where the dissolved carbon dioxide can gather. At these numerous “anchor points,” the CO2 dissolved in the liquid rapidly changes into its gaseous form (bubbles). This explosive increase in gas volume pushes the trapped Coke (liquid) up and out all at once. That’s the secret behind the Mentos-Coke eruption!
In this experiment, perhaps because we used only one Mentos in 300ml of Coke, the eruption was relatively slow and gentle. This is similar to a real-life volcanic eruption (like Hawaii’s Kilauea) where low-viscosity (runny) lava flows out quietly.
What if you want a more spectacular eruption? Well, maybe increasing the number of Mentos, warming the Coke (but be careful not to overheat it!), or changing the type of Coke (some say Diet Coke gives different results due to different sugar content) might change the outcome.
I encourage everyone to try this safely in a secure location, always with an adult! And if you think about why this happens, your usual snack time will become a whole lot more interesting! If you want to go even bigger, here’s another recommended method that doesn’t use Mentos and must be done outside:
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