Information about Diet Coke & Mentos with Fizzics Education | Kids Science Experiments

Why does Mentos & Coke bubble?

Why does Mentos & Coke bubble?

Follow FizzicsEd 150 Science Experiments:

You Will Need:

A parent’s help

1 Bottle of diet coke

1 Nail or small hand drill



Outside space


Mentos and diet coke science experiment - materials needed using supermarket goods
1 Mentos and diet coke science experiment - pushing a nail through a plastic lid

Drill a small hole through the lid of the bottle. Pour out the first 5cm of Diet Coke for extra working room.

2 Mentos and diet coke science experiment - drilling a cap with mentos nearby

Use the needle to thread the string through four Mentos, leaving a 10cm length of sting trailing off the Mentos Bundle.

3 Mentos and diet coke science experiment - threaded string and coke bottle lid

Thread the trailing string length through the bottle cap. Pull the string tight, so that the Mentos bundle is up against the lid. Don’t let go of this string yet!

4 Mentos and diet coke science experiment - string of mentos inside coke bottle

Carefully screw the lid onto the bottle, making sure that the Mentos do not touch the Diet Coke.

5 Mentos and diet coke science experiment - diet coke and mentos reacting

Find an area that can get wet. When you’re ready, release the string!

Why Does This Happen:

We are often asked how this experiment works when we visit schools.
Many students have come to believe that it is a chemical reaction between the Mentos carbonates and the Diet Coke acids that makes the fountain work… however, it turns out that research findings have turned up a quite different explanation; the reaction is largely physical, not chemical.

Diet Coke has a massive amount of dissolved carbon dioxide in the liquid. When you open a Diet Coke bottle, the gas is released instantly, i.e. bubbles form. How does this happen? The solution is actually super-saturated with gas – the gas would escape the liquid if it wasn’t for the high pressure within the unopened bottle. Opening the bottle allows the gas to be released.

Bubbles can also form on tiny points on the surface of a container, known as nucleation points, or site. When you pour a carbonated drink into a glass, the very fine scratches on the glass cause the bubbles to be formed on the tiny nucleation points along the scratches of the glass.

A Mentos has many, many fine scratches on the surface; a perfect place for bubbles form. Dropping a Mentos into Diet Coke allows the dissolved gas within the liquid to come out of the solution extremely quickly, courtesy of the many nucleation points on the Mentos surface.

Learn more!


Leave a Reply

Your email address will not be published. Required fields are marked *

This website uses cookies to improve user experience. By using our website you consent to all cookies in accordance with our Cookie Policy.