Coke & Mentos Experiment
Launch a fizzy soda fountain outdoors and learn why tiny candy surfaces make gas rush out fast.
Introduction
Get ready for a sky-high splash because this experiment can make soda shoot up like a rocket fountain.
It is exciting to watch, and it also teaches you a real science idea that looks almost like magic.
The Why
Soda has carbon dioxide gas dissolved inside it. Mentos candies have lots of tiny bumps that give the gas many places to escape at once, a process called nucleation, so the soda rushes out fast. Diet Coke usually works better than regular Coke because it has less sugar and is not as thick, so the bubbles can race upward more easily and make a taller geyser.
Step-by-Step Instructions
- 1
Go outside to an open area like a driveway or yard and put on safety goggles.
- 2
Set the soda bottle on flat ground where it will not tip over.
- 3
Open the bottle and get your Mentos ready as quickly as you can.
- 4
Stack 5 or 6 Mentos in a paper tube or hold them above the bottle opening with an index card under them.
- 5
Pull the card away so all the Mentos drop in at the same time.
- 6
Step back right away and watch the soda fountain blast upward.
- 7
Talk about what happened and measure which soda or number of Mentos made the biggest geyser.
Materials List
- 1 two-liter bottle of Diet Coke or other soda
- 1 roll of Mentos
- An open outdoor space
- Safety goggles
- A piece of paper or an index card
- Optional: a tube or paper roll to help drop the Mentos together
Safety First!
Do this experiment only outside and stand back as soon as the Mentos drop in. Never point the bottle at people, and do not drink the soda after the experiment.
Challenge Mode
Test two different sodas and compare which one makes the taller fountain.