How does a fuel cell separate the oxygen from the other elements in the air (considering that ambient air is a logical oxygen source for a fuel cell)?thnx ;)
ambient air isn't used as the oxygen source for a fuel cell - sorry, I can't go into more detail than that.
The other gases in ambient air are unreactive in a hydrogen fuel cell. The earth's air contains: 78% nitrogen (virtually unreactive in all conditions) 20.95% oxygen (natural oxidant) 0.93% argon (unreactive) 0.04% carbon dioxide 0.08% mixture of other trace gases So the oxygen content in air is about 200 times greater than any other gas that might react with the hydrogen. Also, being a natural oxidant, it is the preferred gas for the hydrogen ion to react with.
Well, generally speaking, a hydrogen fuel cell (HFC) is used to burn hydrogen, combining it with oxygen to produce electrical power (watts) and water (waste product). The process doesn't really need to be selective in the sense of filtering. Rather it depends on the chemical reactivity of the oxygen. As the oxygen comes in contact with the hydrogen via the PEM (proton exchange membrane), the reaction becomes more a matter of surface area. The more oxygen available, the faster the reation can occur, but other gases in the air are generally unable to react in any manner. Most of the air you breath is made up of Nitrogen, and this does not burn very well. Other rare gases, such as Argon, Xenon, Neon, etcetera, are either Nobel Gases (unreactive), or are simply not as easy to react with as Oxygen is! And because of the miscibility of the gases (they tend to be equally distributed, rather than forming pockets or clusters of isolated gases), the oxygen is readily available. :)
