Blog of Random Thoughts and Pictures

Research behind what really is behind the Diet Coke and Mentos physical reaction?

June 12th, 2008

Just picked up this interesting item from the NewScientist on the Science of Mentos-Diet Coke explosions explained which has taken its cue from the American Journal of Physics paper “Diet Coke and Mentos: What is really behind this physical reaction?”
According to the author, its not totally down to the chemical reaction of the ingredients in the sweets, and the ingredients in the Coke, its also got to do with microscopic dimply surfaces of the Mentos which disrupts the attractions between water molecules hence encouraging bubble cascading.

But didn’t the guys from MythBusters already solve this one? [1]
Well one explanation may be that research papers do not get published at Internet speed! The paper was received 7 June 2007; accepted 5 February 2008, published June 2008. The MythBusters show aired on August 9, 2006 ……… hmmmm hang on a second that doesn’t quite match up, but I see back in the comments field for this article the author is defending their work.
The paper looks at items:-

such as the importance of the speed with which the samples fall through the soda and the soda temperature. I also rigorously quantify the effects of surface roughness of the samples and the changing surface tension of the liquids, using nanoscale microscopes and contact angle measurements. I credit the Mythbusters in the paper for identifying the primary ingredients (and I love their show), but they did not really go into the WHY behind the reaction as much as I do in the paper.

Mores the point who would have thought a PhD dissertation on “Nanotribology Fundamentals: Predicting the viscous coefficient of friction” would lead to explaining this.
I’m a believer that the devil is in the detail.
Einstein in one of his early papers answered the simple question : How can you measure sugar molecules dissolved in a cup of tea? His formula for measuring the size of sugar molecules in a liquid was applicable to all molecules and provided much of the framework essential to his analysis of Brownian motion [pdf].
Okay okay I’ll finish .. it’s still interest though.
[1] Embedding disabled by request