Remember when you would do cool science experiments as a kid? You could use lemon juice to write invisible messages. You could make homemade slime from Borax (cleaning product) and glitter glue. Or you could go with a classic and build your own volcano out of clay, drop some baking soda and dish soap in the opening, then add vinegar and boom! watch it erupt. These were fun as kids but we probably all outgrew them by the time we were 6.

drinking baking soda and vinegar gif.gif

Believe it or not, putting baking soda in your mouth then drinking vinegar does the same thing.

One science experiment that will never be outgrown is dropping mentos into coke and watching it explode. This trick never gets old because the reaction is incredible. When the candies are dropped into the carbonated beverage it causes the coke to suddenly spray out if it’s container.

The exploding soda trick has been around since the early 1980’s when science teachers would drop wintergreen Lifesaver candies into coke bottles to show their students the characteristics of CO2. I guess Lifesavers didn’t like their candies being used for science and learning because they deliberately made the wintergreen Lifesavers a little bigger so they couldn’t fit into the opening of a soda bottle. This caused the science teachers of the world to search for something else and they found something much better; Mentos. Mentos are Scotch mints (hard shell with a chewy center) made by the company Perfetti Van Melle, first produced in the Netherlands in 1948. And they are perfect for making soda burst out of its bottle.

The very first time the Mentos and Coke experiment was televised was in 1999 on the Late Show with David Letterman when Lee Merek and “Merek’s Kid Scientists” demonstrated it live. Then in 2005, tv personality and science teacher, Steve Spangler did the experiment on TV and the clip went viral on YouTube. This was when the experiment became insanely popular in the public. Kids were doing their own versions at home. People filmed their experiments and uploaded them to YouTube as well. The very popular science show at the time called Myth Busters did a whole episode about it.

So WTF is Happening?

Why does dropping Mentos in Coke cause it to fizz up so much? You would probably think it’s a chemical reaction between the ingredients of the soda and the ingredients of the mint but you would be wrong. It’s actually a physical reaction called Nucleation. What’s happening is when Mentos are dropped in the soda all the CO2 (Carbon dioxide) molecules cling to the mint and since the Mentos’ surface area is full of microscopic ridges and pits the CO2 molecules form into gas very rapidly.

All those tiny bubbles trapped in the soda are looking for a way out. They are drawn to any tiny bumps they can grab onto and fizz up. These are called nucleation sites and a single Mentos has millions of them. That’s why the surface area of soda bottles are plastic or glass. They are always smooth so the soda can’t fizz up uncontrollably. This is also why you cannot do the experiment with a fruit flavored Mentos. These kind are covered in a wax coating making it’s surface area smooth so the CO2 has nothing to grab onto.

By the way, the same things happens in your mouth.

So what happens when you fill a whole aquarium full of Mentos and Coke?

In a YouTube video by the channel Power Vision, they filled a whole aquarium half with Mentos and half with Coke with a barrier in-between. They then pulled the barrier out for the two to mix.

Watch what happens… (3:20 is when they do the Mentos & Coke Experiment)

If you were kind of disappointed with the result you’re not alone (just read the comments of the video). There’s a few reasons why the coke explosion wasn’t as big as everyone thought.

The first reason is that they are using regular Coke in the video. For better results the preferred soda is Diet Coke. It’s better because the food additives in Diet Coke (not Coke) like potassium benzoate, aspartame, sugars and other flavorings react to the gelatin and gum arabic of the Mentos to aid in the increased foaming, especially aspartame (sugar substitute) because it reduces surface tension in the liquid that causes a bigger reaction.

Another reason it wasn’t a huge geyser everyone was expecting was because it wasn’t in a bottle. The aquarium had a huge opening for the CO2 bubbles to escape. Whereas if it was in a giant bottle the opening would be a lot smaller causing more pressure to build and rocket the soda out. However, the video got over a 100 million views in a week so I think they are happy with what they did.

So there you have it. Now you know the science behind Diet Coke and Mentos geysers. Next time you and your friends are bored, go out and entertain yourselves with this trick. To end this article I’ll leave you with an awesome GIF of a man making a Coke & Mentos rocket.

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