Featured Research

from universities, journals, and other organizations

Students Explore The Physics Of Fizz

Date:
June 13, 2008
Source:
Appalachian State University
Summary:
Just about everyone knows what happens when you drop Mentos mints into a Diet Coke. Students have documented why the reaction occurs by studying the physics responsible for the fizzy result and had the results published in the American Journal of Physics.

Just about everyone knows what happens when you drop Mentos mints into a Diet Coke.
Credit: Michael Murphy, courtesy Wikimedia Commons

Just about everyone knows what happens when you drop Mentos mints into a Diet Coke.

Students at Appalachian State University have documented why the reaction occurs by studying the physics responsible for the fizzy result. Their results have been published in the June 2008 issue of the American Journal of Physics.

Tonya Coffey, an assistant professor of physics at Appalachian, developed the research project to as a way for sophomore-level students to build on skills they learned in their freshmen physics courses.

Through a series of experiments, the students found that a reaction between the rough surface of the Mentos, and the potassium benzoate and aspartame contained in Diet Coke were responsible for the famous geyser reaction, in which the liquid can spew up to 30 feet.

In the process, they also learned about the principles of thermodynamics, fluid mechanics, surface science and the physics of eruptions.

“We try to teach students what real experiments are like,” Coffey said. “I thought it would be good for the students to work on an experiment that doesn’t have a known outcome—because that’s what research is.”

Coffey asked her students to find out everything they could about the Diet Coke and Mentos reaction, develop a question about the reaction and design an experiment to answer their question. The students’ only restrictions were to design an experiment that could be accomplished on a tight budget and to use existing equipment at the university.

“We discussed what a real researcher has to do when designing an experiment to answer a question,” Coffey said. Students studied what makes a good experiment, how complications can arise, the need to narrow the number of unknowns in an experiment, and the importance of designing an experiment that tests for one variable at time.

The students measured the volume of liquid displaced and the distance it traveled when a variety of items were added to Diet Coke – including Mentos, Wint-O-Green Lifesavers, rock salt, table salt and sand.

They also studied the surface roughness of the candy and other materials by using a scanning electron microscope and an atomic force microscope.

So why does the reaction occur? In an opened container of soda, carbon dioxide gas bubbles out over the course of minutes or hours until the concentration of carbon dioxide left in the soda is proportional to the carbon dioxide in the surrounding air. This de-fizzing reaction is slow because the surface tension of the liquid is very high, which keeps the gas bubbles trapped.

But when a Mentos is dropped in the beverage, it breaks the surface tension and as it falls the candy’s surfactant coating further reduces the surface tension of the liquid. The candy’s rough surface also provides growth sites for the gas, making it easier for carbonation to escape as a foam geyser.

The geyser also occurs when sand, salt or lifesavers were added to the Diet Coke, but the mass lost and volume traveled is much less spectacular.


Story Source:

The above story is based on materials provided by Appalachian State University. Note: Materials may be edited for content and length.


Cite This Page:

Appalachian State University. "Students Explore The Physics Of Fizz." ScienceDaily. ScienceDaily, 13 June 2008. <www.sciencedaily.com/releases/2008/06/080612173622.htm>.
Appalachian State University. (2008, June 13). Students Explore The Physics Of Fizz. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2008/06/080612173622.htm
Appalachian State University. "Students Explore The Physics Of Fizz." ScienceDaily. www.sciencedaily.com/releases/2008/06/080612173622.htm (accessed July 29, 2014).

Share This




More Matter & Energy News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
Powered by NewsLook.com
Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Newsy (July 28, 2014) Stanford University published its findings for a "pure" lithium ion battery that could have our everyday devices and electric cars running longer. Video provided by Newsy
Powered by NewsLook.com
The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins