The mentos/cola experiment has reached new heights. Details are in the study:
“Probing the Mechanism of Bubble Nucleation in and the Effect of Atmospheric Pressure on the Candy–Cola Soda Geyser,” Thomas S. Kuntzleman and Ryan Johnson, Journal of Chemical Education, epub 2020. The authors, at Spring Arbor University and at Doherty High School, Colorado Springs, Colorado, report:
The so-called Diet Coke and Mentos experiment is initiated by dropping Mentos candies into a bottle of Diet Coke or other carbonated beverage. This causes the beverage to rapidly degas, causing foam to stream out of the bottle. Simple application of the gas laws leads to the straightforward prediction that ejection of greater foam volume is expected at lower atmospheric pressure. This hypothesis is bolstered when principles of bubble physics are taken into account. This hypothesis was tested and confirmed by monitoring the foam produced during the Diet Coke and Mentos experiment at various altitudes above sea level.
Author Tom Kuntzleman sent us this lovely note:
Ryan Johnson and I recently examined the effect of altitude (and therefore atmospheric pressure) on the Diet Coke and Mentos experiment. To do so, we carried out the experiment in many places around the US at altitudes that ranged from below sea level in Death Valley to over 14,000 feet at the top of Pikes Peak. We had an absolute blast.
For my father’s day present in 2019, my family gave me permission to carry out Coke and Mentos experiments at various locations (elevations) as we traveled through Arizona, California, Nevada, and Utah for summer vacation.