Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Students Explore the Physics of Fizz

13.06.2008
Students use the principles of physics to explain the Mentos-Diet Coke reaction.

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.

Tonya Coffey | newswise
Further information:
http://www.appstate.edu

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>