Mentos & coke experiment science experiment : Fizzics Education


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Mentos & coke experiment

Mentos & coke experiment

Follow FizzicsEd 150 Science Experiments:

You Will Need:

  • A parent’s help
  • 1 Bottle of diet coke
  • 1 Nail or small hand drill
  • String
  • Scissors
  • Outside space
  • Needle


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 using a hand drill or a nail. Pour out the first 5cm of Diet Coke for extra working room.

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

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

Thread the trailing string length through the bottle cap. Tie a knot on the end of the string behind the mentos so they can’t fall of the string.

Pull the string tight, so that the Mentos bundle is up against the lid. Don’t let go of this string yet!

3 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.

4 A bottle of diet coke erupting with bubbles in a carpark

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

6 Teacher showing how to do an experiment outside to a group of kids.

Online courses for teachers & parents

– Help students learn how science really works

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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.

Variables to test

More on variables here

  • Try different numbers of Mentos… how high can you make it go?
  • Try different soda drinks. Which carbonated drink make the Mentos eruption go higher?
  • What happens if you use cold vs. room temperature soda drinks?
  • Does using different flavours of Mentos produce any measurable difference in how high the eruption is?

A man with a glove above a liquid nitrogen vapour cloud

Learn more!


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