The Famous Coke and Mentos Eruption

By: Courtney Horvat, Gary Kleinschmidt,

and Casey Kelby

Steve Spangler began the phenomenon when he appeared on 9 News in 2002 and again in 2005

Eepybird.com continued the trend when a video featuring Fritz Globe and Stephen Voltz recreated the eruption with multiple fountains mirroring the fountain display at the Bellagio in Las Vegas

History of the Myth, the Fountain, the Legend…

Besides becoming an almost instant internet trend, it has also been seen on a variety of TV shows including Numb3ers, Bones, and Myth Busters

Many websites feature Mentos and coke video contests

Eepybird.com even provides step by step instructions (Thank you!) and sells merchandise

History Continued…

World Record: 1,911 simultaneous geysers by students of Latvia’s School of Business Administration Turbia

When you drop the Mentos into the soda, the gelatin and gum Arabic from the dissolving candy break the surface tension. This disrupts the water mesh, so that it takes less work to expand and form new bubbles. Each Mentos candy has thousands of tiny pits all over the surface. These tiny pits are called nucleation sites - perfect places for carbon dioxide bubbles to form. As soon as the Mentos hit the soda, bubbles form all over the surface of the candy.

Couple this with the fact that the Mentos candies are heavy and sink to the bottom of the bottle and you've got a double-whammy. When all this gas is released, it literally pushes all of the liquid up and out of the bottle in an incredible soda blast. (Steve Spangler Science)

How does it work?

We went out and bought 40 bottles of Sprite and 40 bottles of coke (16 oz), Then we bought a few 6-packs of Mentos rolls

We made a stand out of scrap wood to angle the bottle at 45° from the horizontal to give the best trajectory and used a rubber band to fasten the bottle to the stand

We made cartridges out of bottle caps with holes in them, and strung Mentos on fishing line to eliminate errors when dropping in the Mentos

Our Experiment…

Then we would place the bottle on the stand, quickly take off the cap, replace it with the cartridge and release the Mentos

Then we would measure the furthest spray To measure weight, we measured the

weight of the soda (weight of bottle minus weight of empty bottle, then compared it to weight of fluid in full bottle)

What Happens Next?

We wanted to see whether the Diet Coke and Mentos eruption would go farther than the Sprite and Mentos eruption, as stated on Eepybird.com

Go the distance: Diet Coke vs. Sprite

Perrier, Coke, Sprite, Diet Coke. (Wikipedia)

Go the Distance

1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839400

50

100

150

200

250

300

350

Diet Coke Distance (inches)

Sprite Dis-tance (inches)

Diet Coke

Sprite

Mean 237.0 173.5Standard Deviation

9.28 50.7

Min 56 36Q1 216.3 148.3Median 250.5 182.0Q3 275.2 209.1Max 313 253IQR 58.8 60.8

Go the Distance

40696.50525.173

409686.582.237

::

s

s

s

dc

dc

dc

sdc

sdc

nSxnSxHaHo

17865.522

s

s

dc

dc

sdc

nS

nS

xxt

Go the Distance: Two-Sample T-test

7108265.8)2831.76|17865.5( dftP

We reject Ho because p-value at 8.8265×10-7 is < α=0.05. We have sufficient evidence that the difference between the average of diet coke is greater than the average of sprite.

Assumptions:2 independent SRS → assumedNormal population or n≥30 → n=40≥30

Go the Distance: Two Sample t-interval

)163.88,187.39(*)(22

s

s

dc

dcsdc n

snstxx

We are 95% confident that the difference in the average spray distance of Diet Coke and Sprite is between 39.187 and 88.163 inches.

For our second experiment, we wanted to see if the eruption displaced half of all the liquid, so we weighed the liquid and tested our results…

How much weight is dissipated in the Diet Coke & Mentos eruption?

Min: 5.4 Q1: 10.4 Med: 11.4 Q3: 12.275 Max: 12.9 Mean: 10.906 Std. Dev.: 1.753

Does it loose half its weight?

3905.40

71479.10726.115.:5.:

df

nSxxHaHo

d

d

d

d

1583.41

nSxt

Does it lose half its weight?Matched Pairs T-test

34104951.9)39|15823.41( dftp

We reject Ho because p-value at 9.4951×10-34 is < α=0.05. We have sufficient evidence that the average difference of net weight after the eruption is not equal to half the original weight.

Assumptions:2 dependant SRS → assumed

(before and after)n≥30 → n=40≥30

Does it lose half its weight?Matched Pairs T-test

621.11,524.10*

nstx d

d

We are 95% confident that the average difference in the net weight of the liquid remaining in the bottles after eruption of Diet Coke and Mentos is between 10.524 and 11.621 fluid ounces.

Weather/ Temperature◦ Heat as a factor in

experiment: the warmer the better

◦ Wind Exact measurements

◦ Scale◦ Measuring Spray

Drilling/Threading◦ Cracked some shell and

lost some of nucleation sights

Overspray under cap◦ Not enough time to

screw it on all the way Fishing line caught,

hands in the way Shaken soda/CO2

released between cap exchange

Holes in cap caused angle in spray

Bias/Error

Overall the project was fun and interesting with all the science behind it

While we may have had errors and biases, we performed our experiment to the best of our ability

We feel that our results are accurate and that our methods helped us to achieve our accuracy

How we feel…

Diet coke is the best soda to use out of the Sprite/Diet Coke test

When doing a Diet Coke and Mentos experiment, the net weight loss will not equal half of all the weight

Application to the Population