Question to Explore:
How can we create a reaction using Mentos and Diet Coke?
- pack of Mentos
- piece of paper
- index card
- new bottle of Diet coke
Part 1: Prepare the Mentos
- Cut a piece of paper so that it is as wide as a roll of Mentos.
- Wrap the paper around the pack of Mentos to make a tube. Tape the tube closed. Remove the pack of Mentos from the tube.
- Open the pack of Mentos and place all of them in the tube.
Part 2: Make the Mentos and Soda Fountain
- Slowly and carefully open a new bottle of Diet Coke.
- Place it on a flat area outside where it is OK to get wet with soda.
- Put one end of your tube of Mentos on an index card and place it directly over the opening of the soda bottle.
- When you are ready, remove the card and let all the Mentos drop into the soda at once and quickly move out of the way.
Click the play button below to see this experiment in action!
Follow up Questions:
- What kind of reaction is created during the eruption? How do you know?
- Does the size of the coke bottle determine the size of the reaction?
- Does soda other than Diet Coke work? Why does Diet Coke work best?
- Does candy other than Mentos create a reaction?
Diet coke is full of carbon dioxide gas, which bonds with water. When soda is inside the bottle, the gas remains in the Diet coke/water solution. When poured into a glass, the foam you see at the top is actually the carbon dioxide gas escaping. However, most of the gas remains trapped by the surface tension of the water. In order to create bubbles, the carbon dioxide’s bonds with water in the Diet coke must be broken.
Mentos candy helps break apart the bonds between the Diet coke and the water! The rough surface of the candy allows the carbon dioxide gas and the water to break apart, creating the carbon dioxide bubbles that cause the eruption. When Mentos are dropped in very quickly, it creates a bigger reaction. You can also compare the size of the reaction when pouring in whole vs. crushed Mentos.
The eruption created in this experiment is caused by a physical reaction (not a chemical one like that of baking soda and vinegar) because all of the pieces of the reaction are still there.
Learn more with these resources!
American Chemical Society – Adventures in Chemistry
Two scientists have done lots of AMAZING experiments with diet coke and mentos. Check out their other at-home experiments as well.
Materials photo: https://www.sciencebuddies.org/stem-activities/diet-coke-mentos