Diet Coke and Mentos: Clash of the Titans

This time... it’s personal

Simon Barton

Evan Vallejos
Table of Contents

The materials required for a Diet Coke and Mentos lab may be more than one would expect. Firstly, a partner is highly recommended to reduce error percentages. The other materials needed are: many, many 2-liter bottles of Diet Coke, a couple crates of mint flavored Mentos, a thermometer, a video camera, a tripod, chalk or tape to mark height in video analysis, and a safe method of heating and of cooling the Diet Coke. In other words, standard household appliances are a must. For our research we chose to heat water to a near-boiling temperature on a stove, and then placed the Diet Coke in the hot water, periodically checking the temperature until it was exact. For cooling the Diet Coke, we placed the 2-liters in a freezer over night, then once frozen, we removed them and periodically checked the temperature until it warmed to the correct degree. Once the Diet Coke was at the correct temperature, it was simply a matter of carrying it to the side of a house, which has been marked with chalk in increments of one foot, going all the way to twenty feet. A partner, who has been stationed at the video camera directed at the side of the house then records as the other physicist places five Mentos into the Diet Coke and instigates the fizzy explosion. The more intimate details of the camera set-up will be provided in the setup diagram. The process of heating or cooling the Diet Coke must be performed a minimum of eight trials per temperature for accuracy. For our research, we chose to measure the geysers at ten different temperatures starting at zero degrees Celsius and increasing the temperature in increments of five, so up to forty-five degrees Celsius. Once all eighty trials of Mento-Coke explosion were recorded on video and uploaded to a computer, we simply used Vernier’s software: LoggerPro to analyze the peak height of every geyser, and recorded our data. The average of all eight trials was calculated and counted as the expected height of a geyser when the Diet Coke is heated to that temperature. Warning: Heated plastic or carbonated beverages is extremely dangerous when done carelessly.

.:. Setup | To da topz

.:. Results | To da topz

Our data results were a clear indication of a trend of increase in geyser height as the temperature increased. Overall, unless there was a major error, the difference was noticeable even without video analysis, clearly the geysers were taller and taller. There were no general calculations or equations that had to be used to record our data, but rather simple measurements. The following is a scatter graph of the data with a link to the raw data.

Data file: text .:. Excel

.:. Conclusion | To da topz

The results were exciting and distinguished from the very beginning. Well, maybe not the very beginning. As a frozen Diet Coke ice cube, the explosions were literally next to nothing. However, once the Diet Coke was a freezing-cold liquid, it started to produce a very small bubbling geyser. As the temperature increased, the height began to increase. The first increment of increase from 0 Celsius to 5 Celsius yielded the greatest increase in height. More than likely, the less solid chunks of ice in the bottle, the faster the Diet Coke can escape from the bottle. Also, our hypothesis was determined correct. As the temperature of the bottle decreased, so did the height of the geyser, and vice versa. This trend is more than likely because of the kinetic energy within each molecule in the Diet Coke bottle, including potassium benzoate, aspartame, and caffeine, all of which are the main reactants that cause the fizzy explosion. Although there were no general formulas or calculations that had to be made, but instead measurements, an equation could still be applied to the situation. The equation E=1/2mv^2 can be applied to every molecule, and as the temperature in the bottle increases, the velocity squared increases the energy dramatically, and demonstrates an entertaining effect. We acknowledge that sources of error within the lab include but are not limited to wind blowing the geyser slightly, temperature inaccuracies while using the thermometer, heat lost from the bottle while transporting it from inside the house to outside of the house, although the cap sealed the heat for the most part, or by not placing one of the five Mentos within the Diet Coke fast enough, and lastly choosing a smart location to place the bottle every time. After about half the trials were conducted several bottles started tipping over before the peak of their eruption due to severe wind, thus we were unable to accurately calculate the volume of Diet Coke left over after the eruption. However, up until that point the general trend showed that unless the bottle was completely frozen over, the remainder of liquid was completely random. It often fluctuated from almost empty at 10 C, and would also keep a half-full bottle of liquid fizz after a 20 C explosion. Thus we considered the remaining volume possibility a moot subject. We also decided that the bottles tipping was best solved by continuing the trials on days with fair weather. Improvements in the procedure could have included an ideal location for explosion, conducting the experiment on a hotter day and in a hotter location, and moving the bottles to the location as quickly as possible.

.:. Links | To da topz

http://en.wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption - Wikipedia article on Diet Coke and Mentos. Very informative, but somewhat general and unspecific.

http://eepybird.com/dcm1.html - Describes Coke and Mentos on a grand scale and includes specific examples of experiments that relate to Diet Coke and Mentos.

http://www.zap2it.com/tv/news/zap-mythbustersmentos,0,4325641.story - Results from example experiment and information from our friends at Mythbusters.

http://www.youtube.com/watch?v=LjbJELjLgZg - Video trials of the experiment. Once again, our Mythbuster friends detail what is important about the reaction.

http://www.newscientist.com/article/dn14114-science-of-mentosdiet-coke-explosions-explained.html - Video analysis of Diet Coke and Mentos. Also, article detailing the relevant information involved with the reaction.