What Happens When You Drop a Mentos Into Coke?

What to expect

When you drop a Mentos into a bottle of Diet Cola, it's said that the result will be a massive eruption of cola and CO2 gas. Countless videos on the Internet show this experiment done by people of all ages.

Oftentimes, people will drop the Mentos directly into a two-liter bottle of diet cola, with the end result being a geyser of soda propelling itself into the air. This experiment can be extremely messy, and should be done outdoors.

How it works

According to MythBusters, the process that causes this reaction is called nucleation. Since each Mentos is covered in little grooves, it has a lot more surface area than it would if it were smooth. As the carbonation of the soda hits the Mentos, the CO2 quickly changes to gas. This fast-acting reaction triggers a response that generates gas at an incredibly rapid rate, resulting in a massive eruption of gas and cola.

The fact that the Mentos sinks when it hits the cola is also significant, as most of the gas formation in soda happens at the bottom.

Other possibilities

Another suggested reason for this reaction has to do with arabic gum. It is said that this chemical found in Mentos causes the surface tension of the soda to drop. This drop in surface tension then makes it easier for the gas to escape, and results in a more rapid eruption.