Contributed by: Sarah F
Date of Publication: September 30th 2011
Why do Mentos and Diet Coke react? You may believe that there is some chemical in the Mentos, or some gas in the Diet Coke that makes the two react in a chemical reaction. Although actually this is a physical reaction, which means that all the components of the reaction are there.
Figure 2 - Diet Coke Erupting

The first component is the saturated solution which in this case is a carbonated beverage or soda. All the bubbles that make
Figure 1- Mentos Causing Diet Coke To React
you burp come from a carbon dioxide gas that is dissolved in the solution. While the soda is in the bottle or can the gas stays there because of the pressurized conditions inside the bottle or can. When you pour some soda into a cup the gas bubbles stay there because of surface tension. All the gas bubbles are sitting there waiting to escape.

The second component is the nucleation site; in this case it is the Mentos candy. If you look at a Mentos candy you would
think that the Mentos is smooth. Although if you were to look at the Mentos under a microscope then you would see that the Mentos is covered in billions of tiny bumps. Each of those bumps acts like a nucleation site, a place where a gas bubble can get a kick start and escape. Every single nucleation site is a place where a gas bubble can escape the solution, if you multiply that by all of the bumps on the Mentos you have yourself a Diet Coke geyser.

If you use more Mentos, therefore you would have more nucleation sites, than you will have a taller eruption because you will have more places where a gas bubble will escape. Also if you make the nucleation sites larger you will have a taller eruption because the kick start that the gas bubble gets will be slightly larger.

The Difference of Physical and Chemical Changes
Changes that substances go through can be called Physical or Chemical changes. A Physical change is when the physical appearance of a substance changes although the substances basic identity does not change. An example of a Physical change would be when water evaporates. The water becomes gas and the physical appearance changes although the water is still water although in a different form. Changes of state (for example, from liquid to gas) are physical changes.

In Chemical changes a substance is changed into a different substance. An example could be when you burn steel wool (which is very close to simple iron) it oxidizes (a chemical reaction). The left over material is smaller than the steel wool but weighs more since the iron becomes iron-oxide. Complete changes of substance are chemical changes.

1300 Students Set Mentos and Diet Coke Fountain Record

Once in a Belgian city 1300 students set the record for diet coke and mentos fountain. 1360 cokes were set off
Figure 5 - Diet Coke And Mentos On The Road
Figure 3 - Belgian Students Setting Off Cokes
coke shot up more than 29 feet high. This occasion attracted at least 10 million viewers.



  1. To form into a nucleus.
  2. The initial process that occurs in the formation of a crystal from a solution,a liquid.


  1. Existing, occurring, or operating at the same time.


  1. To convert (an element) into an oxide; combine with oxygen.


Brown, Bursten, Lemay. Chemistry the Central Science Sixth Edition. Englewood Cliffs, New Jersey. Paramount Communications Company, 1991. Print.

"Coke and Mentos--Nucleation Goes Nuclear!." Science News for Kids (2007): 2. Science Reference Center. EBSCO. Web. 20 Sept. 2011.

Wikipedia. “Soda and Candy Eruption”. Wikipedia the Free Encyclopedia. Wikipedia, 12 September 2011. Web. 20 September 2011.

"nucleation." © Encyclopedia Britannica, Inc.. Encyclopedia Britannica, Inc.. 23 Sep. 2011. <Dictionary.com http://dictionary.reference.com/browse/nucleation>.