A carbonated beverage, like soda, is packed with carbon dioxide gas that is dissolved into the soda solution and bonds with water. While the soda is in the bottle, the gas is kept in solution by the pressurized conditions inside the bottle. To create bubbles, the carbon dioxide needs to interact with itself, which means that its bonds with the water in the soda must be broken. A Mentos® candy can help with this.
Each Mentos® candy has thousands of small pores on its surface which disrupt the polar attractions between water molecules, creating thousands of ideal nucleation sites for the gas molecules to congregate. This means that each tiny pore acts like a place where the physical reaction can get a kick start; this is where a bubble of carbon dioxide gas can form and escape!
As the Mentos® candy sinks in the bottle of soda, the candy causes the production of more and more carbon dioxide bubbles. The buoyancy of the bubbles and their growth will eventually cause the bubbles to leave the nucleation site and rise to the surface of the soda to escape.
Bubbles will continue to form on the porous surface and the process will repeat, creating an enormous foamy geyser!
Mentos and Coke
Jered Richter, Laura Houlberg, Dayna Kam, Aubrey West
Table of Contents:
Mentos and Coke are our generation's Baking Soda and Vinegar. Made famous by internet videos, and Mythbusters in 2006, it was thought that this effect was a reaction of what happens when the gum arabic and gelatin, caffeine, potassium benzoate, and aspartame is combined. What actually happens during the reaction has yet to be figured out, but most people agree on a popular explanation. The reaction works like this: each Mento has thousands of nucleation sites, tiny surface pits, which make a perfect place for the formation of carbon dioxide bubbles. When the Mentos and Coke combine, the bubbles start a huge reaction. Some fountains can be almost ten meters high. The gas is released and pushes the Coke up to the top with great force. There isn't a lot of research done about Mentos and Coke yet, since it is a new phenomenon.
Question: What is the relationship between the number of Mentos used and the height of the geyser which the reaction produces?
Our group wants to find out the relation between how many Mentos are used, and how high the fountain sprays. We want to know what kind of function this relation follows.
Hypothesis: If we plot the heights of the geysers in relation to the number of Mentos used, then it will produce a graph similar to that of a root function.
We hypothesize that the plotted points will follow the pattern of a square root function, which would show a steep increase at first, and then even out the farther we go along the x-axis. In the experiments done by Fritz Grobe, and Stephen Voltz, the geysers topped out at eight meters. When Mythbusters did their experiment, they set a record at twenty-nine feet (9 meters). We do not expect our geysers to reach these heights, because we do not do this on a regular basis, as do Grobe and Voltz. It will be easier for us to make mistakes, such as letting too much carbon dioxide out before we drop the Mentos.
• 12 bottles of Coke
• 78 Mentos
• Sticky notes
• Meter stick
• Video analysis program (Logger Pro)
• Geyser tube
• Video camera
Independent: Number of Mentos
Dependent: Height of geyser
Constants: Volume of Coke, shape of bottle, temperature of Coke, Mentos' style of entry
1. Set up a video camera to film the experiment
2. Measure and mark one meter and two meters on vertical surface next to Coke bottle, to create a reference for distance when using video analysis
3. Put the appropriate number of Mentos into the geyser tube and insert pin into hole to keep the Mentos from falling out
4. Quickly open Coke bottle and insert geyser tube with Mentos into opening
5. Remove pin from tube, letting Mentos fall into bottle. Hold tube with your hand so that it stays relatively vertical inside neck of bottle
6. Allow geyser to reach maximum height, and then die down
7. Repeat steps 3-6 with a new bottle of Coke each time until you have done a trial for the following numbers of Mentos: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12
8. Use Logger Pro to find heights of geysers each trial, by using video analysis with the videos taken during experiment
Table of Heights:
# of Mentos Height of Geyser (m)
Data file: text .:. Excel
Note: x-axis = Number of Mentos, y-axis = Height in Meters.
This graph does a good job revealing the relationship between the number of Mentos put in a Coke and the height which the geyser will reach. At first when a Mento is added, it affects the results dramatically. As the number of Mentos grew, the impact of each additional Mento decreased. This outcome makes sense for the following reason: At the beginning of the experiment, the ratio of Mento to Coke was very small and this meant that another Mento would greatly affect the ratio, but as the ratio grew, the effect got smaller and smaller. For example, if you go from 1 Mento/ 1 Liter of Coke to 2 Mentos/ 1 Liter of Coke, then the amount of surface area the Coke can reach on the Mentos is doubled, or in other words, increased by one 100%; however, if you go from 11 Mentos/ 1 Liter of Coke to 12 Mentos/ 1 Liter of Coke then you are only increasing the surface area by 9%.
After conducting our experiment and analyzing our results, we found that our hypothesis was correct. When we graphed the height of the geyser depending on the number of Mentos we dropped in the coke bottle, it strongly resembled a root function. The height increased significantly when we started out and slowly started to top out as we increased the number of Mentos.
Review of Experiment:
Sources of error includes the loss of carbon dioxide that was released in the time elapsed between when we removed the cap of the coke bottle and when we dropped in the Mentos. Also, when there was a higher amount of Mentos, the geyser would push some back up and out of the tube. If we were to conduct this experiment again, we would find another method of inserting the Mentos in the coke bottle in order to release less carbon dioxide and keep the Mentos inside of the Bottle. We could also try different types of soda to see how and if that would affect the geyser.
"The Chemical Physics of Food" by Peter Belton
Various videos on Youtube.com and the Eepybird.com site
Other Related Sites:Top
Just another Coke and Mentos video
The mythbuster's explanation of Coke and Mentos
Using Coke and Mentos for a Volcano
How to make a rocket with Coke and Mento's
Coke and Mentos bomb! Just for kicks.