# Phase diagram of oxygen

Discussion in 'General Science' started by magnet18, Jul 23, 2011.

1. ### magnet18 Thread Starter Senior Member

Dec 22, 2010
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Hey, does anyone know where I can find a phase diagram for oxygen with some level of detail to it? Google is letting me down.

OR, if anyone happens to just know this kind of stuff, what pressure would I have to get oxygen to in order to liquefy it with dry ice?

2. ### Wendy Moderator

Mar 24, 2008
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While I can't help you, I will throw out something I find interesting. When pumping liquid nitrogen one of the hazards is an oxygen fire. This is because atmospheric oxygen condenses on all the pipes of fixtures from the liquid nitrogen as liquid oxygen, like water on a cold glass.

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3. ### magnet18 Thread Starter Senior Member

Dec 22, 2010
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yep, liquid nitrogen is the most common way to make liquid oxygen, but I can't make liquid nitrogen, so I need to make due with dry ice, which means I need to cycle pressurizing and cooling, which is where my question stems from.

4. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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5. ### someonesdad Senior Member

Jul 7, 2009
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Here are some thermodynamic data from Reynolds, "Thermodynamic Properties in SI". You can see the "vapor dome" and read off e.g. the atmospheric pressure properties at the bottom of the graph (0.1 MPa is 1 bar == 1 atm). Or, you can read what you want from the tabular data.

I'd imagine if you're really interested in the phase diagram, head to a university library and find it in the literature.

In the 70's I was once testing a big stainless steel weldment used in a vacuum system; it was a liquid nitrogen trap. We had a number of LS160 containers in the lab, so I had all the LN2 I needed -- I ran many gallons of LN2 through that trap, which was sitting on a bed of Styrofoam. It's hard to remember, but I think I was after thermal expansion data, as I was designing the chamber the thing went into. Anyway, after the test was over, I had the tech take the trap away and the styrofoam container had around a liter of liquid oxygen that had condensed in it. It was a beautiful pale blue against the white Styrofoam. That's the only time I've gotten to mess with liquid oxygen. I just took it into the hallway and dumped it on the linoleum so that it would evaporate -- but it would be fun to conduct some experimentation with exothermic reactions, such as folks have done with cheap amorphous carbon...

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6. ### magnet18 Thread Starter Senior Member

Dec 22, 2010
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Doh,
I feel dumb now, it would go to supercritical phase, wouldn't it.
hmm... maybe I could place the dry ice in alcohol to cool the alcohol beyond the 198K where dry ice sublimates... but everything would bank on the dry ice having an internal temperature below 154k

Dec 22, 2010
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