Really random question...any chemistry whizzes?

[alyssab93]

Heyy everyone!! so for my chemistry class I did a presentation on the element helium, and something struck my mind as I was presenting that I would like to know. Helium is harmful to a human because it causes a lack of oxygen. If it is harmful to the body, why is it used in artificial atmospheres for deep-sea divers? Any info is appreciated!

P.S. sorry this is so random, but I thought that it doesn't hurt to ask!! ;D

[Nancy]

Helium is used in scuba tanks to dilute oxygen. Why helium? First, it is chemically inert, that is to say, it does not participate in chemical reactions. Second, helium is much less soluble in water than many other gases, such as nitrogen. The low solubility means it does not enter the blood stream, even under pressures commonly experienced by deep sea divers.
Under water, a scuba diver is subjected to added pressure. In shallow water the pressure difference is not so great, and one can simply use compressed air to breathe. However, at a depth of 300 feet, a diver experiences nearly 10 times normal atmospheric pressure. Under these conditions, breathing compressed air can be harmful. The increased pressure requires an inert gas to be used to dilute oxygen.

Oxygen is essential for breathing, above and beneath the surface. However, one can get too much of it. Under high pressures, greater amounts of oxygen enter into the bloodstream. If the concentration becomes too high, oxygen poisoning can result, with symptoms that include confusion, impaired vision and nausea. So, under high pressures, oxygen must be diluted with some other gas.

Nitrogen is very abundant and relatively inert, but it cannot be used to dilute oxygen in scuba tanks. At the elevated pressures experienced by divers, larger amounts of nitrogen will dissolve in the blood causing nitrogen narcosis. Dissolved nitrogen also can cause a painful condition, called "the bends" if a diver makes too rapid an ascent. As the pressure decreases, the dissolved gas can form bubbles that can stop circulation in capillaries and damage the nervous system.

[alyssab93]

thanks so much nancy! added some exalt for this post! ;D

[Nancy]

You're welcome! I just Googled it! haha

[pkaugust]

Nov 9, 2009 17:43:47 GMT -5 Nancy said:

Helium is used in scuba tanks to dilute oxygen. Why helium? First, it is chemically inert, that is to say, it does not participate in chemical reactions. Second, helium is much less soluble in water than many other gases, such as nitrogen. The low solubility means it does not enter the blood stream, even under pressures commonly experienced by deep sea divers.
Under water, a scuba diver is subjected to added pressure. In shallow water the pressure difference is not so great, and one can simply use compressed air to breathe. However, at a depth of 300 feet, a diver experiences nearly 10 times normal atmospheric pressure. Under these conditions, breathing compressed air can be harmful. The increased pressure requires an inert gas to be used to dilute oxygen.

Oxygen is essential for breathing, above and beneath the surface. However, one can get too much of it. Under high pressures, greater amounts of oxygen enter into the bloodstream. If the concentration becomes too high, oxygen poisoning can result, with symptoms that include confusion, impaired vision and nausea. So, under high pressures, oxygen must be diluted with some other gas.

Nitrogen is very abundant and relatively inert, but it cannot be used to dilute oxygen in scuba tanks. At the elevated pressures experienced by divers, larger amounts of nitrogen will dissolve in the blood causing nitrogen narcosis. Dissolved nitrogen also can cause a painful condition, called "the bends" if a diver makes too rapid an ascent. As the pressure decreases, the dissolved gas can form bubbles that can stop circulation in capillaries and damage the nervous system.

I gave you some exalt too, this was cool to read - we're learning about "the bends" in Ecology.

[Nancy]

Aw thanks!