The connectivity of Concept

Today, I was mulling over some ideas to write about. I was drawn to the article that I saw in BBC Science about a mountain range in Antarctica that is below the ice cap. It is certainly not the “Mountain of the Blue Moon” from the book Lost Horizon, however, a unexplored mountain is still very intriguing – even if it is under an ice sheet. Here is the address for this article: http://news.bbc.co.uk/2/hi/science/nature/8420837.stm .

I have also been thinking about a short video clip that I saw in my Science methods teaching class. This video showed a kid experimenting with Mentos and diet coke. Here is the link for the Wikipedia page on that experiment: http://en.wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption .

After looking at both, it turns out that I do not have to choose as both ideas have a common theme! What could a kid exploding experiment and a buried mountain chain have in common you wonder? Well, the answer is a concept called nucleation.

Here is the deal on the diet coke / Mentos experiment:

“MythBusters concluded that the caffeine, potassium benzoate, aspartame, and CO2 gas contained in the Diet Coke and the gelatin and gum arabic ingredients of the Mentos all contribute to the jet effect. In addition, the MythBusters theorized that the physical structure of the Mentos is the most significant cause of the eruption due to nucleation”.

And here is the deal on the Antarctic Mountain range:

It led many to speculate that the Gamburtsevs might be old "hot spot" volcanoes that had punched their way through the Earth's crust, much like the Hawaiian Islands have done in the middle of the Pacific.

The range has since become the subject of intense scientific fascination because it was almost certainly a nucleation point some 30 million years ago for the huge ice sheets now covering Antarctica.

So, what exactly is nucleation anyway? Well, here is a brief description:

“Nucleation is the extremely localized budding of a distinct thermodynamic phase. Some examples of phases that may form via nucleation in liquids are gaseous bubbles, crystals, or glassy regions” Available: http://en.wikipedia.org/wiki/Nucleation .

To me, the most interesting thing is that these two seemingly totally unrelated phenomenons have a common physical theme. In many ways, it showcased a reason for us the study aspects of science that may seem impractical. Most of us will never have to worry too much about the genesis of an Antarctic mountain range and I think that it is safe to say that we will never need to challenge ourselves with erupting soda pop.

It is interesting to note, however, that there are many other instances of nucleation. The following is a list of examples of nucleation:

• Pure water freezes at −42°C rather than at its freezing temperature of 0°C if no crystal nuclei, such as dust particles, are present to form an ice nucleus.

• Presence of cloud condensation nuclei is important in meteorology because they are often in short supply in the upper atmosphere (see cloud seeding). From my recent Meteorolgy class, I would add that the most recent theories suggest that rain cannot fall without a condensation nuclei as condensed liquid water is bouyant in the atmosphere/

• All natural and artificial crystallization process (of formation of solid crystals from a homogeneous solution) starts with a nucleation event.

• Bubbles of carbon dioxide nucleate shortly after the pressure is released from a container of carbonated liquid. Nucleation often occurs more easily at a pre-existing interface (heterogeneous nucleation), as happens on boiling chips and string used to make rock candy. So-called Diet Coke and Mentos eruptions are a dramatic example (as mentioned above).

• Nucleation in boiling can occur in the bulk liquid if the pressure is reduced so that the liquid becomes superheated with respect to the pressure-dependent boiling point. More often nucleation occurs on the heating surface, at nucleation sites. Typically, nucleation sites are tiny crevices where free gas-liquid surface is maintained or spots on the heating surface with lower wetting properties. Substantial superheating of a liquid can be achieved after the liquid is de-gassed and if the heating surfaces are clean, smooth and made of materials well wetted by the liquid.

• Nucleation is relevant in the process of crystallization of nanometer sized materials,and plays an important role in atmospheric processes.
• Nucleation is a key concept in polymer, alloy, and ceramic systems.

• In chemistry and biophysics, nucleation can also refer to the phaseless formation of multimers which are intermediates in polymerization processes. This sort of process is believed to be the best model for processes such as crystallization and amyloidogenesis.

• In molecular biology, nucleation is used to term the critical stage in the assembly of a polymeric structure, such as a microfilament, at which a small cluster of monomers aggregates in the correct arrangement to initiate rapid polymerization. For instance, two actin molecules bind weakly, but addition of a third stabilizes the complex. This trimer then adds additional molecules and forms a nucleation site. The nucleation site serves the slow, or lag phase of the polymerization process.


That is quite a lot of examples that tie in the Mentos / Coke kid and the submerged mountain range!

As we educate our children in science, it is difficult, sometimes, to see the value in watching of doing experiments like the coke explosion. However, we can see from the list, that if the right connections are made, not only can science be fun; it can also lead to concepts that will enhance our society and also further the development of science and technology in our world.