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is oxygen perishable?

Postby dcboroja » Sun Apr 04, 2021 12:12 pm

I'm not a student, but I'm an avid trekkie with an inquisitive mind! I have exhausted all google searches and cannot find a definitive answer :(

if you were to seal a room, make it airtight (but with breathable air within), and access it after a thousand years, would you still be able to breathe that air? is the compound which makes up our breathable air perishable? does it deteriorate in any way?

ref: star trek tng: season 3, episode 6

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Re: is oxygen perishable?

Postby Baldcoach » Fri Apr 09, 2021 12:02 pm

Hello DC Borja,

I'll take a stab at that question even though I'm not one of the site experts. It seems to me that you are asking if Oxygen remains Oxygen after thousands of years. The answer is....maybe, the answer depends on what is in the air with it, the temp of the room, and what the room is made out of. Also, the amount of hard radiation in the room will have an effect given enough time.

So, here we go. Nitrogen (78% of 'normal' air) will spontaneously react with Oxygen to form 2 molecules of NO at about 7500C. So if your room is very warm AND has an Earth-like atmosphere, you could expect there to be detectable amounts of NO in the air in thousands of years. But, this reaction is very NOT spontaneous at lower temperatures, so the amount produced will be vanishingly small (not a technical term...but it fits). The reaction would occur, and would produce some NO, but the NO would also start breaking back down into Nitrogen and Oxygen, so the amount would not increase after a while unless the temp or concentrations of gasses changed.
If the walls of the room were made of virtually any material that could oxidize then over thousands of years they certainly would. Oxygen is a VERY reactive chemical (electronegativity 3.5). This uses up breathable O2 molecules to form oxygen compounds (like rust). So, there would be less oxygen in the atmosphere after the oxidation of the material happened than before. Still, unless the room was half full of iron filings, that probably wouldn't make the atmosphere unbreathable.
If the room is subject to lots of radiation then we could have a problem.
Energetic radiation could 'bust up' the nuclei of the Oxygen and create new elements. Given enough time and enough hard radiation you might find the air unbreathable. Simple UV radiation can break the bond between oxygen atoms in an oxygen molecule (possibly leading to the formation of Ozone...not breathable) and more energetic radiation could, theoretically, knock protons out of the nucleus of Oxygen atoms so that they aren't Oxygen any more.

I have probably forgotten to consider some things...but there is my best shot. Basically, if the room is free from lots of ionizing radiation and oxidizable chemicals, I'd expect there to be plenty of oxygen left unless you are baking the inside like an oven.

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Re: is oxygen perishable?

Postby lil_chapstick » Fri Apr 30, 2021 1:03 pm

no. it is not perishable.

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