The American Journal of Physics has an article in the June issue about the physics of dropping Mentos into Diet Coke. The spectacular result depends on physical characteristics of the Mentos, not their chemical composition. Here’s an explanation from the 60-Second Science podcast.
5 thoughts on “What makes the Mentos-Diet Coke trick work”
Kids love it! I recommend the cheapest diet soda you can find, and do it outside on the lawn of course.
When I was a kid I noticed how plain sugar does this, too.
I’ve got a sand blaster (for prepping metal for epoxy) in the garage — I guess if I take it to some rocks or steel I ought to get some really good ‘mentos’ for the geyser!
I think Mythbusters “published” first. With the same explanation. Nucleation. Except that Mythbusters found that table salt was even more explosive.
My kids were not nearly intrigued by this as me. It’s what happens when you get a Masters in PChem.
Similarly, I’ve heard there has been an increase in ‘explosive’ sparkling water bottles, where one opens an undisturbed bottle and it suddenly erupts in a geyser. Still not too common, but modern factory production and the use of plastics means that typically there are many fewer nucleation sites inside the bottle since it is so clean and smooth.
I’ve only seen the ‘mythbusters’ show once and wasn’t too impressed — they did a very limited and simplistic experiment and determined the myth was busted.
The same thing happened with regards to spontaneous human combustion until the real (ordinary and non-supernatural) explanation was demonstrated. That explanation had been ‘tested’ many times by folks like the mythbusters and ‘proven’ to be impossible.
Until someone actually did it with a pig carcass.
I love the Mentos Geyser experiment! I did it with my son and he loved it. We tied in some science behind it and learned about chemical reactions. We found another great website with cool fun free science projects like this. I will post the link below for anyone who is interested.
my group and i are doing a project about it