Whether the soda is warm or cold, the process of forming bubbles occurs slowly. However, if there are sharp edges or fine particles in the liquid, these have surfaces that allow the CO 2 molecules to start bubble formation more easily these are called nucleation points. Mentos tablets contain thousands of these nucleation points and when dropped into Coke, they allow the bubbles to form almost instantaneously.
To understand how the surface of the Mento causes the CO 2 bubbles to nucleate, think about how rock candy is made. A string or a stick is immersed into a supersaturated mixture of sugar and water, and crystals of sugar nucleate around the stick. Without immersing the stick, the crystals will grow eventually, but the stick speeds up the process by providing a surface for nucleation. This pressure effect of gases and liquids also has a more dangerous aspect as well: when scuba divers go to great depths in the ocean, they are breathing air, or specialized gas mixtures, at four or more times atmospheric pressure.
Because of this, nitrogen dissolves into their blood stream in much higher amounts than would happen at the ocean surface. The exploding water in the garbage can demonstrates what happens when a gas, which is confined by pressure, is released suddenly: it expands very rapidly, blowing out everything in its way. The gas used in this experiment is liquid nitrogen, which was carefully anchored beneath the water. Do not try this at home!
Liquid nitrogen should only be handled by experts. Aside from the microscopic structures on the outside of the Mentos shells, there are several chemicals that make Coca-Cola explode in this way. These chemicals are found in the shell itself as well as in the soda mixture, and they contribute to the formation of pressurised foam. Here are some of the chemicals that make up the shell:.
These ingredients act as surfactants and help accelerate the release of carbon dioxide gas. Surfactants lower the surface tension between two liquids, a liquid and a solid, or between a gas and a liquid. So, when a Mento is dropped into some Coke, the acidity of the soda mixture quickly dissolves its shell, releasing the chemicals.
Their surfactant properties then lower the surface tension of the Coke, which breaks apart the water molecules and, in doing so, allows carbon dioxide bubbles to form more readily. With this in mind, the chemicals in Mentos also serve as foaming agents by facilitating the rapid release of CO 2 gas. Various types of carbonated beverages react differently with Mentos: Seltzer water has the weakest reaction while, very specifically, Diet Cherry Dr.
Pepper has the strongest reaction. This was demonstrated in an experiment that tested 15 types of carbonated beverages with Mentos. Each bottle tested had a two-litre capacity, and eleven Mentos were introduced to each bottle. A two-litre bottle has about 15 grams of dissolved carbon dioxide, which, under the right conditions, becomes 8 litres of carbon dioxide gas in just a few seconds. The types of solutes in the soda mixture also have effects on the height of the fountain.
An experiment on Seltzer water, adding various types of solutes, produced the following results:. This mixture was first formulated by an American pharmacist, John S. Step 3: Hold your finger over one end of the paper tube and have your child fill it up with Mentos mints.
It will probably hold a pack and a half of mints. Check that the paper is unbent, so that the mints will easily fall from the end of the tube when you remove your finger. Step 4: Hold the tube of mints over the mouth of the bottle. Older kids can do it themselves. For more quick tips and book recommendations, sign up for our Scholastic Parents newsletter! This causes pressure to build in the bottle and send a spectacular jet of bubbles shooting into the air.
0コメント