in this lesson, you have learned how important the gas laws are e.g. during scub
ID: 1016541 • Letter: I
Question
in this lesson, you have learned how important the gas laws are e.g. during scuba diving. During scuba diving, the divers breathe pressurized air. Some freedivers (these are divers that dive without the use of pressurized air tanks!!!), on the other hand, can descend as deep as ~ 200m, without using additional oxygen! How comes that freedivers don't need to worry as much about decompression of their lungs compared to their scuba-diver friends? Make sure to be specific and to use the nomenclature learned in this lesson.
Explanation / Answer
When you are scuba diving, you are breathing compressed gas typically at a mixture of 79% Nitrogen and 21% Oxygen. When you breathe from a scuba tank, the air coming out of the tank actually has the same pressure as the pressure that the water is exerting. It has to, or it won't come out of the tank. Therefore, when SCUBA diving, the air in your lungs at a 33-foot depth has twice the pressure of air on land. At 66 feet, it has three times the pressure. At 99 feet, it has four times the pressure, and so on. When high-pressure gases in the air come in contact with water, they dissolve into the water. This is how carbonated beverages are made. To make carbonated water, water is exposed to high-pressure carbon dioxide gas, and the gas dissolves into the water. We all know what happens when you release the pressure in a bottle of soda -- bubbles suddenly start rising. The gas dissolved in the water at high-pressure comes out of the liquid when the pressure is released, and we see it as bubbles. So if a scuba diver stays under water, say at a depth of 100 feet (about 30 meters), for a certain period of time, some amount of nitrogen from the air will dissolve in the water (bloodstream & tissues) in his or her body. If the diver were to swim quickly to the surface, it is just like uncorking a bottle of soda -- the gas is released. This can cause a very painful condition known as the bends, and it is sometimes fatal. To avoid the effects of quick decompression, the diver must rise slowly and/or make intermittent stops on the way up (called "decompression stops") so that the gas can come out of solution slowly. If the diver does rise too fast, the only cure is to enter a pressurized chamber in which the air pressure matches the pressure at depth (breathing 100-percent oxygen on the way to the chamber also helps). Then, the pressure is released slowly. If the diver decompresses properly, remains at "recreational depths" (less than 100 feet or so), and is careful about the air supply, the dangers can be largely eliminated. Proper training, good equipment and careful execution are the keys to safe diving.
Freedivers won't breath or release gases from lungs (PV = constant) hence there is no decompression of gases from their lungs, that freedivers don't need to worry as much about decompression of their lungs compared to their scuba-diver friends.
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