Stand Back! I’m Going to Try Science!

Mentos and Diet Cola

The following is an experiment that demonstrates scientific concepts, that can be conducted in the back yard, kitchen, or classroom, and that is a lot of fun for learners of all ages.

Concept:

This experiment will demonstrate a type of chemical reaction called nucleation.  This is a great demonstration for a chemistry class, but is also so much fun that even if you don’t study chemistry, it is worth trying.

For This Experiment You Will Need:

Two-liter bottle of diet cola

Mentos candy (it works the best and is the fresh-maker!)

A test-tube

A small piece of card-stock

An outdoor area

A towel (most likely)

Directions:

  1. Load the Mentos into the test-tube.
  2. Open the diet cola bottle.
  3. Place the card on the opening of the test-tube.
  4. Turn the card and test-tube upside-down so that the candies are resting on the card.
  5. Place the card over the opening of the diet cola bottle.
  6. Remove the card and allow the candies to fall into the diet cola.
  7. Stand back and be amazed by the awesome power of chemistry!
  8. If you didn’t stand far enough back while being amazed, use the towel to dry off.

Here is a video of some surprised TV presenters trying the experiment.

Safety Tip: don’t leave the cap on the diet cola.  It is our understanding that the bottle will detonate with equivalent force of 1000 tons of TNT.  Or maybe it will just spray everywhere and take the fun out of it.

He left the cap on.

What Did We Observe?

Short Answer: Bubble-splosion!

Pictured: One Bubble-splosion

Slightly Longer Answer: Nucleation (causing a visible bubble-splosion)

Scientific Answer: While it appears smooth, on a microscopic scale, the surface of the candy is actually quite rough and covered in tiny nooks and crannies.

I don’t know which is a nook and which a cranny.
(Image courtesy of newscientist.com)

This rough surface provides an ideal place for the carbon dioxide molecules in the cola to rapidly convert into gas.  As the candy sinks, and more bubbles are produced and forced to the surface, the pressure will build and cause the bubbly fluid to shoot out of the top of bottle.

Here at Enable, we love two things: Science and moustaches.  This is why we have such a warm spot in our hearts for the Mythbusters.  A few years ago, they decided to get to the bottom of the science behind diet cola and Mentos, and here is what they found (click here if the video doesn’t appear below):

A quick Google search and you will find that there are thousands of videos of people trying variations of this experiment, and taking this to its logical conclusion.

Conclusions:

  1. The rough surface of the Mentos candies makes it perfect for nucleation of the carbon dioxide in the cola, causing the aforementioned bubble-splosion (if I keep saying it, eventually it will be a recognised word)
  2. If you sit in paint before a big meeting, try and make the paint look like pinstripes.  You’ll be sure to impress your boss and earn the respectful salute of the incompetent handyman who neglected to put up a sign warning you of the wet paint.
This guy has it all figured out.

 3. Enable Education ♥ the Mythbusters, and hope that someday they ♥ us right back.

So, there you have it: a fun experiment that you can do at home or school.  Give it a try, get messy, learn something, and have some fun.

If you liked this adventure, check back with us next week when we will be presenting more ideas for easy to do science experiments.

Andrew Baxter is a Secondary School Teacher and Curriculum Specialist with Enable Education.  He has no formal education in chemistry, but drinks a lot of diet cola, and therefore should be considered an expert. 


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