This summer, we were looking for a bunch of fun ridiculously messy things to do with our kids; we finally tried the Mentos and Diet Coke experiment!
We tried this with a small 20 ounce soda from the fridge case at the checkout at the grocery store first, and it really has to be a full 2 liter of soda. We've read it works best with warm soda, not cold. We got some great results with room temperature and are excited to try it again with a bottle that's been sitting in the sun to see if it's more epic!
Here's the basic science behind how it works:
The bubbles in soda are carbon dioxide gas. That gas bonds with the water in soda and they hang out together like best buddies. Mentos look really smooth, but under a microscope are covered in tiny pores that actually give it a rough texture. That rough texture breaks up the gas from the water as it gets dropped into the soda, and all that carbon dioxide rushes out of the opening of the soda bottle. There's so much gas escaping all at once it causes an epic explosion!
According to my reading on the subject, Mentos will create this eruption in any soda but works best in diet soda. The aspartame in the diet soda reduces the surface tension of the liquid, allowing the escaping air to get through easier.
You'll notice if you try this that the reaction starts pretty much the second the Mentos hits the Diet Coke - to get as many Mentos in the bottle as quickly as possible, we just hot glued all the candies in the pack together in a stack and dropped it in.
If you haven't seen EepyBird's amazing Mentos and Diet Coke video from 2006, you totally need to - you can see it here: https://www.eepybird.com/featured-video/the-extreme-diet-coke-mentos-experiments/
We hope you enjoy this experiment as much as we did!