The soda fountain: A startling reaction between coca-cola and mentos

Your stomach will explode if you eat mentos and drink coke at the same time. Ever heard of this? Is that true? Let's find out! 

You must have seen a very famous video on social media as a fun science experiment in which the moment mentos mint is dropped in a bottle containing coke, an explosion occurs. Why does that happen? Does that same reaction occur in your stomach too? Ever wondered about the chemistry behind this? Let’s unravel the concept behind this. 

Mentos gyeser

What are the constituents of coca-cola? 

1. Water

2. Carbon dioxide 

3. Sugar or sweetener 

4. Caffeine 

5. Caramel color 

6. Phosphoric acid 

7. Natural flavors 

Coca-cola is nothing but carbonated water and a mix of several chemicals. Carbon dioxide gas is pumped into the soda and the bottle is sealed under high pressure. Once you open the soda bottle, the dissolved gas tries to escape (that is what makes you burp) and gives that pleasant sound (Ah! The fizz). 

First things first, this explosion is not a consequence of a chemical reaction between Coca-Cola and mentos, as sodium bicarbonate reacts with vinegar, but a physical reaction. A physical reaction within the beverage releases dissolved gas, causing this spectacle.

Dropping Mentos in soda (Source: Solugen)

What happens when you drop mentos in coke? 

Water molecules are bound to carbon dioxide gas in the bottle which prevents gas molecules to bind with each other and forming bubbles. The moment you drop mentos in the soda bottle, the bond between water and carbon dioxide molecules becomes weaker and carbon dioxide attaches to the mentos. The tiny bumps, craters, and pores on the surface of mentos (it may look smooth if observed by the naked eye, but it is not) allows carbon dioxide to attach to its surface more easily and form bubbles. This bubbling process is called nucleation and the surface of mentos acts as a nucleation site.

Surface of Mentos
(Source: Mikkel Juul Jensen Science photo library)

In simple words, think of mentos candy behaving as a site on which carbon dioxide molecules will accumulate thereby increasing the pressure. The bonds between carbon dioxide gas and water break more easily, causing carbon dioxide bubbles to form. All this pressure has to release and before you know it, it spurts out and shoots in the air forming a soda fountain. The highest recorded explosion is of mentos with diet coke forming a fountain of up to 10 meters. Several types of carbonated beverages react differently with mentos. The fountain height depends on various other factors such as the speed with which the mentos is dropped in the bottle, temperature, pressure, and other solutes.

 

The eruption (Source: Solugen)

Coming back to our very first question, will our stomach burst if we eat mentos while drinking soda? Actually not, the moment you eat the candy its rough surface dissolves so you will not get the same eruption in your stomach. Moreover, most of the carbon dioxide is released into the atmosphere when the person is drinking soda therefore there is not enough gas pressure for nucleation.

You can also perform this fun experiment. All you need is a bottle of coke, mentos, and a large open space (it is a messy experiment).