Bubbles are Delicious!

The Chemistry of Bubbles

There are many, many types of bubbles. The folks at Wikipedia have a pretty exhaustive list, which can be found here

Bubbles are not easy things to understand. They are created through a complicated phenomenon known as the Marangoni effect. There are a great many articles and studies done and being performed to better understand the Marangoni effect. Why all the effort to understand bubbles? Their properties are unusual and quite useful. Our knowledge of the Marangoni effect has been applied to the fields of welding, crystal growth and electron beam melting of metals, to name a few

As an example, integrated circuits (used in computers and nearly every other digital device with any computational capabilities) use an alcohol vapor to prevent water spots. This is done to the silicon wafers during their production; these wafers are used in the circuits. The application of the alcohol uses the principles of the Marangoni effect.

So what is the Marangoni effect? From Wikipedia:
"Since a liquid with a high surface tension pulls more strongly on the surrounding liquid than one with a low surface tension, the presence of a gradient in surface tension will naturally cause the liquid to flow away from regions of low surface tension. The surface tension gradient can be caused by concentration gradient or by a temperature gradient (surface tension is a function of temperature).
As an example, wine may exhibit a visible effect called "tears", as shown in the photograph. The effect is a consequence of the fact that alcohol has a lower surface tension than water. If alcohol is mixed with water inhomogeneously, a region with a lower concentration of alcohol (greater surface tension) will pull on the surrounding fluid more strongly than a region with a higher alcohol concentration (lower surface tension). The result is that the liquid tends to flow away from regions with higher alcohol concentration — along the tension gradient. This can also be easily demonstrated by spreading a thin film of water on a smooth surface and then allowing a drop of alcohol to fall on the center of the film. The liquid will rush out of the region where the drop of alcohol fell."

Wikipedia also has articles on soap bubbles, liquid bubbles, and "antibubbles." From the article on soap bubbles:
"A soap bubble can exist because the surface layer of a liquid (usually water) has a certain surface tension, which causes the layer to behave somewhat like an elastic sheet. Soap film is extremely flexible and can produce waves based on the force exerted. However, a bubble made with a pure liquid alone is not stable and a dissolved surfactant such as soap is needed to stabilize a bubble. A common misconception is that soap increases the water's surface tension, soap actually does the opposite, decreasing it to approximately one third the surface tension of pure water. Soap does not strengthen bubbles, it stabilizes them, via an action known as the Marangoni effect. As the soap film stretches, the surface concentration of soap decreases, which in turn causes the surface tension to increase. Thus soap works by selectively strengthening the weakest parts of the bubble, preventing any one part of the bubble from stretching excessively."

Wikipedia defines a liquid bubble thus: "A bubble is a globule of one substance in another, usually gas in a liquid." "Antibubbles" then are pockets of liquid surrounded by a film of gas, and are called antibubbles because their interior is filled with a liquid, rather than air.

The physics behind bubbles are yet more complex, and as scientists learn more about them, they come to understand more about how the world works. Everything from the boiling process of water to new methods for reducing heat can be understood by learning the principles that govern bubbles and the Marangoni effect.

To learn more about the chemistry of bubbles, try visiting the Bibliography and selecting a link from the Chemistry section.