[Why do all of my posts start with "So,"? Anyway, moving on...]
Steve is a science educator, Director of the National Hands-on Science Institute in
The theory of why soda erupts out of the bottle when you drop Mentos candies into it is available on Steve Spanger's Science website, Wikipedia, and probably several other places, but the general idea is approximately as follows:
- Soda is bubbly because there is carbon dioxide (CO2) gas disolved in the sweetener / water / other chemical solution.
- The surface of a Mentos candy is covered with some huge number of itsy bitsy little pits and craters and spikes and stuff.
- When the soda comes in contact with the sharp edges of the candy, nucleation sites are formed (more on that here) where the carbon dioxide comes out of solution with the rest of the soda and causes a chain reaction of rapidly expanding gas that forces the soda up and out of the bottle.
- It's also handy that the candy sinks to the bottom of the bottle so that it has to force the soda up instead of just the gas coming out the top and foaming a bit (like when you drop ice cream into root beer).
So basically, it's just a physical reaction of the CO2 and soda coming out of solution, not a real chemical explosion. The soda isn't really altered in any way, other than it comes out of the bottle and does not have any carbonation left.
There are plenty of good videos on YouTube that (sometimes) show this in action. One nice adaptation is this one of two French guys making rockets out of soda bottles.
As an interesting side note to this whole thing, Mentos appears to be a big advertising winner, while Coke is a huge looser. Mentos estimates the free marketing generated by the viral-video phenomenon to be worth $10 Million in marketing, while Coke Spokeswoman Susan McDermott says, "It's an entertaining phenomenon. We would hope people want to drink more than try experiments with it." And that "craziness with Mentos doesn't fit with the brand personality."
Wowzers. When I try it this weekend, I'm gonna use Pepsi. Or store brand.