P599: Investigation of the origin of the Diet Coke and Mentos reaction

Author: Albert D. Dukes, III, Lander University, USA

Co-Author: David E. Gardner, Lander University, USA

Date: 8/5/14

Time: 2:05 PM2:25 PM

Room: MAK BLL 126

Related Symposium: S47

We investigate the origins of the Diet Coke and Mentos classroom demonstration. This is an engaging demonstration and is very popular with students. With video analysis, we measure geyser height and reaction time as a function of number of candies used as well as the temperature of the soda. Our results show that the maximum geyser height is linearly related to temperature over a broad range of temperatures. In addition, we show that the geyser process is more complicated than the commonly given explanation indicating that the geyser results solely from the ability of the candy surface to nucleate CO2 bubbles. We propose that the geyser is a result of a two-step process. By better understanding the geyser process, the Diet Coke and Mentos demonstration can be more effectively used as a teaching tool.