TESTING TO DETERMINE THE BEST CONDITIONS TO TURN A SODA AND
MENTOS GEYSER INTO A SQUIRT GUN
Cate Pitterle
Cary Academy
ABSTRACT
These experiments were performed to determine if and how a Diet Coke and Mentos geyser
could be made into a squirt gun. The original experiment was testing different sizes of Diet Coke
to see which produced the best geyser. It was hypothesized that the squirt gun would be able to
be made with a 2-liter bottle held at 120 degrees away from the body, but when transferred to a
new bottle, the Diet Coke would not produce a geyser. The Geyser Tube was attached to the
Coke bottle and the Mentos loaded into it. The string on the Geyser Tube was pulled and the
geyser shot up. The 2-liter bottle produced the best geyser. Two extension experiments were also
performed, one of which was to test what angle the squirt gun should be held at to produce the
best geyser. The soda bottles were held at different angles and the original experiment
preformed. When held at 120 degrees away from the body, the shot went the farthest. The last
experiment was a relationship experiment testing whether or not Diet Coke would produce a
geyser when poured into a new bottle. The experiment was performed by pouring all of the Coke
out of one 2-liter bottle and into another and performing the original experiment. The experiment
worked, but the geyser was lower. It was concluded that a Diet Coke and Mentos geyser could be
made into a squirt gun, but only under the right conditions.
INTRODUCTION
The purpose of this experiment was to test to find out the best conditions under which a soda and
Mentos geyser can be made into a squirt gun.
It was observed that the Diet Coke was brown in color and foamed when shaken. It had 0 grams
of protein. Diet Coke had no calories. The Diet Coke had 46 mg of caffeine and it was loaded
with CO2. The Diet Coke fizzed a lot when it was shaken, and Diet Coke wasn’t bitter and had a
sweet aftertaste. The Mentos were heavy and seemed like they would sink. The Mint Mentos
were very hard and not chewy at all, like the packaging claimed, and tasted rather like mint
toothpaste.
It was researched and found that the Diet Coke and Mentos geyser was a physical change, or a
change where the molecules are rearranged, but not their internal structures. This is much
different than a chemical change, where the internal structures of a molecule change and new
substances are created. In the Coke and Mentos geyser, the Mento(s) pushes the Coke molecules
away and up, but the molecules themselves do not change.
One individual made a diet Coke and Mentos squirt gun by dropping three Mentos into a twoliter bottle and screwing the cap on, and then hammering a nail into the cap. About 1/4 of the nail
was sticking out from the cap. The bottle was then shaken, and the individual waited until the
foam died down. Then the person quickly took the nail from the cap, keeping a firm grasp on it,
and took it out of the cap. The diet Coke sprayed from the bottle.
The Diet Coke and Mentos geyser was researched to find out how it worked. First of all, the soda
is loaded with carbon dioxide in factories. This carbon dioxide is what makes soda so bubbly.
The bubbles in the soda are locked with water molecules that attract each other and form a net
over each carbon dioxide bubble. The water creates a net and prevents the expansion of bubbles.
Now the Mentos are dropped into the bottle, and the gum arabic and the gelatin breaks the
surface tension of the soda. Bubbles expand and form all over little pits, known as nucleation
sites, on the Mento. The Mento sinks to the bottom of the soda because it is heavier than the
soda. This creates a double-whammy effect, and the soda is pushed out of the bottle in a
spectacular geyser. It was also found that seven Mentos was the optimum number of Mentos to
use in a Diet Coke and Mentos experiment and produced the best geyser.
It was hypothesized that the Mentos can be made into a squirt gun because the pressure will
shoot the liquid out of the bottle. It was also hypothesized that the 2-liter bottle would make the
highest geyser because this is the size bottle most often used for Diet Coke and Mentos geyser
experiments. It was also hypothesized that out of the three angles being used for when the Coke
was made into a squirt gun the 120 degree angle would be the best because it was not at a
straight 90 degree angle away from the body, but was tipped slightly upwards so that the Mentos
could fall into the bottle but not so upwards that the Coke would shoot straight up. For the last
experiment, it was hypothesized that the Diet Coke and Mentos geyser would not work when
transferred to another bottle because the carbon dioxide would be released.
MATERIALS AND METHOD
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12 FL OZ bottle of Diet Coke
16.9 FL OZ bottle of Diet Coke
1.25 liter bottle of Diet Coke
2 liter bottle of Diet Coke
Mint Mentos
Geyser Tube
Bucket
For the first experiment, the regular Diet Coke and Mentos experiment was performed. This
experiment measured the height of the Diet Coke and Mentos geyser with different sized bottles
of Diet Coke. First, 7 Mentos were dropped into the 12 FL OZ bottle using the Geyser Tube. The
Geyser Tube is a plastic tube that attaches to the nozzle of the Diet Coke bottle and drops the
Mentos into the Diet Coke when its string is pulled. The string was pulled and the results
recorded. This was performed next with the 16.9 OZ Diet Coke bottle, and then the 1-liter bottle
was tested. The two-liter bottle was used last. The bucket was used to clean up and the results of
the experiment were recorded. The control for this experiment was the 2-liter bottle because that
is the size bottle most often used for Diet Coke and Mentos experiments. The independent
variable was the size of the bottle and the dependent variable was the volume and height of the
geyser. Three of the controlled variables were the number of Mentos dropped into the Coke
bottle, the flavor of the Mentos, and the brand of soda used.
The 2-liter bottle was used for the next experiment. First, 7 Mentos were dropped into the bottle.
The bottle was held at a 120-degree angle away from the body. The length of the geyser was
recorded. Next, this was repeated, but with the bottle being held at a 100-degree angle away from
the body. The results were recorded and another bottle was then held at 130 degrees away from
the body and the results recorded. The independent variable was the degree at which the bottles
were held and the dependent variable was the length of the geyser. The control was the bottle
held at 120 degrees. The independent variable was the angle at which the bottle was held and the
dependent variable was the length of the shot. Three controlled variables were the size of Coke
bottle, the height at which the bottle was held, and the person holding the bottle.
In the next experiment the Diet Coke bottle was emptied into another bottle to see if the results
would be the same as if it was in the same bottle. First, a 2-liter bottle of Diet Coke was emptied
into another empty 2-liter Diet Coke bottle. Then the first experiment was performed, by loading
7 Mentos into the Geyser Tube and dropping them into the Diet Coke bottle and recording the
results. The independent variable was the Diet Coke as it was poured into the new bottle and the
dependent variable was if the Diet Coke geyser still shot up and if so, how far. The control was
the Diet Coke geyser when made in its original bottle. Three controlled variables were the size of
Diet Coke bottle, the brand of soda used, and the number of Mentos used.
RESULTS AND DISSCUSSION
6
Height of Geyser (m)
5
4
3
2
1
0
12 FL OZ
16.9 OZ
1.25 Liter
2 liter
Size of Coke Bottle
Figure 1: The first experiment tested the size of the Diet Coke geyser with different sizes of
Diet Coke bottles.
For the first experiment, the size soda that shot up at the maximum height was the 2-liter bottle
of soda. The geyser shot up 5.4864 meters, putting the 12 FL OZ bottle, which shot up
approximately 0 meters, in the dust. The 16.9 FL OZ bottle shot up a geyser of about 0.91 meters
and the 1.25 liter bottle shot up a geyser of 4.8768 meters. The size of the bottle seemed to
determine the height of the geyser, even with the same amount of Mentos being used. The
control, the 2-liter bottle, was also the largest bottle and had the highest geyser. The Diet Coke
was generally shot up in a thin stream rather than a thick blast. The Coke didn’t actually shoot
straight up; instead, it often curved when it reached a certain height, which was different for the
different sizes of Coke. Though the 1.25 liter and the 2 liter bottles shot up around the same
height, the 2 liter bottle had a thicker stream than the 1.25 liter, perhaps because there was more
soda in the bottle.
6
Length of Shot (m)
5
4
3
2
1
0
0
20
40
60
80
100
120
140
Degrees that the Bottle was Held at
Figure 2: The second experiment tested the length of the geyser when the bottle was held at
different angles.
In the second experiment, the 120 degree angle produced the best geyser by a long shot. The max
was when the bottle was held at 120 degrees away from the body, and the squirt gun shot 5.1816
meters. It shot in a high arch and fell at the 5.1816 meter mark. At 100 degrees away from the
body, some Mentos did not fall into the bottle and the Diet Coke bottle almost effectively
exploded. Water was pouring out the sides of the Geyser Tube and the Coke went forward about
0.3 meters. At 130 degrees away from the body, the Coke shot straight up and didn’t shoot very
far. It shot about 0.97536 meter after shooting many feet in the air.
Height of Geyser (m)
5.6
5.5
5.4
5.3
5.2
5.1
5
4.9
4.8
4.7
4.6
4.5
Original Bottle
New Bottle
Bottle
Figure 3: The third experiment tested whether there was a relationship of the geyser height
between the Diet Coke being in the bottle that it came in versus being poured into a new
bottle.
For the third experiment, the data from the 2-liter bottle height in the first experiment was taken
and put into a relationship experiment. When the Diet Coke was poured into the new bottle and
the Diet Coke and Mentos experiment preformed, the geyser was observed to be not as high as
when the Coke was in the original bottle, but the experiment still did work, and the Diet Coke
shot up about 4.8768 meters. It was determined that there was a direct relationship in this
experiment.
CONCLUSIONS
The hypothesis was confirmed. A squirt gun can be made out of Mentos and Diet Coke. At 120
degrees away from the body, a 2-liter bottle of Diet Coke was found to be able to shoot 5.1816
meters. Diet Coke might even be poured into a specialized squirt gun in the future made for Diet
Coke and Mentos if the results seen in the second extension experiment stay true. The results
may have turned out the way that they did because no matter what, if there was any carbon
dioxide in the bottle, then the Mentos would create a geyser, and the tricky part is just finding out
how to make that geyser work. One future experiment that could be performed would be to
engineer a specialized squirt gun for this purpose. Another experiment to extend the experiments
done would be to use different flavors of Mentos and see if they affected the geyser, or to break
the Mentos in half to see if that affected the squirt gun. A major finding from the third
experiment was that the Diet Coke could be poured into another container and it wouldn’t lose
all of the carbon dioxide, and a major finding from the second experiment was that the Diet Coke
bottle should be held at a 120 degree angle so that the Diet Coke could travel to its maximum
length.
REFERENCES
Senese, Fred. "What is the difference between chemical and physical change?" General
Chemistry Online. General Chemistry Online, 15 February 2010. Web. 27 January 2014.
Spangler, Steve. "Mentos Geyser Experiment." Naked Edges and Flying Potatoes. Austin:
Greenleaf Book Group Press, 2010. Print.
Wikihow. "How to Make a Coke Squirt Gun." Wikihow. Mediawiki, 2014. Web. 27 1 2014.