The science experiments my children talk about for months afterwards are generally the messy ones, like our splatter patterns, glow in the dark oobleck, baking soda experiments and the well known coke and mento experiment.
If you try this I’d definitely do it outside, it’s VERY messy and sticky.
Coke and Mentos Experiment
We dropped two Mentos into a bottle of normal Cola and Diet Cola. I used the cheapest brands available in our local supermarket.
Once you drop the Mentos into the coke, stand back, it’s VERY explosive. The trick is to drop the mento in as fast as you can. If too much of the fizz escapes before you add the mento the reaction won’t be as good.
Why does the Coke and Mento Rocket work?
There are several theories, but it’s thought that the many small pores on the candy’s surface speed up the release of carbon dioxide (CO2) gas from the soda as they give a larger surface area for the reaction to occur over, causing foam to erupt at a super fast rate.
Any fizzy drink beverage will produce a similar effect, but diet drinks seem to work best, as we found in our investigation. This is most likely due to the particular chemicals in diet drinks.
See Steve Spangler for a much more thorough explanation of this very cool experiment
More Coke and Mentos Eruption Ideas
Investigate to find out if the type of fizzy drink matters.
Test flavoured Mentos instead of mint flavoured.
Investigate to discover what would happen if you left the top off the Cola for a few minutes before adding the Mento?
Use the reaction to power something? Maybe a LEGO car?
Design a device to drop several mentos into the bottle at the same time.