Body inflation

MythBusters reported that when fruit-flavored Mentos with a smooth waxy coating were tested in carbonated drink there was hardly a reaction, whereas mint-flavored Mentos (with no such coating) added to carbonated drink formed an energetic eruption, affirming the nucleation-site theory. According to MythBusters, the surface of the mint Mentos is covered with many small holes that increase the surface area available for reaction (and thus the quantity of reagents exposed to each other at any given time), thereby allowing CO2 bubbles to form with the rapidity and quantity necessary for the "jet"- or "geyser"-like nature of the effusion.

This hypothesis gained further support when rock salt was used as a "jump start" to the reaction. A paper by Tonya Coffey, a physicist at Appalachian State University in Boone, North Carolina, goes into detail on the reasons and physics behind the reaction. Coffey found that the rough surface of the Mentos candy helps speed the reaction. Coffey also found that the aspartame in diet soda lowers the surface tension and causes a bigger reaction, but that caffeine does not accelerate the reaction.

clive2007 wrote:
the diet coke and mentos trick is largely myth in terms of belly bloating. we've all seen the diet coke rockets by using mentos and coke - well that's fine when done in that scenario. With the belly bloating, you swallow the mentos and immediately they are in the stomach which has acid in it, so by the time you swallow the coke, the acid neutralizes the effect you would otherwise see.

Also when you make the coke rockets, the coke is still under pressure which acts as catalyst by many magnitudes in terms of the nucleation caused by the pitted surface of the mentos once they are dropped in.

Mostly the bloating you see with diet coke and mentos is more by the volume of coke drunk and the natural bubbles given off in the stomach by the coke.


Clive