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# What is the specific pressure of a liquid called? Answered

I am more specifically referring to shielding gas for welding, C25 (which is 75% argon, 25% carbon dioxide). How do I find out what pressure the gas will be at a given temperature? This is, of course, assuming that the gas is liquefied and contained. If I left something out (because I don't know a lot about this particular conundrum) tell me, I'll comment back.

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## 3 Replies

Tombini (author)2009-06-12

To calculate the relationship between Temperature and Pressure
(P1xV1)/T1 = (P2V2)/T2
Where P= pressure
V= volume
T= temperature

assuming the volume remains constant;
P1/T1 = P2/T2
you must use STP for P1 and T1 to give you a base for the calculations
(this will basically say that as temperature increases so does pressure proportionally)

NachoMahma (author)2009-04-28

. "At any given temperature, for a particular substance, there is a pressure at which the gas of that substance is in dynamic equilibrium with its liquid or solid forms. This is the vapor pressure of that substance at that temperature." - Vapor Pressure at Wikipedia

frollard (author)2009-04-28

http://en.wikipedia.org/wiki/Boyles_law or the ideal gas law...among others
The pressure, volume and temperature are related.
To liquefy a gas you need one of those variables below the condensation point of that gas - either up the pressure, lower the volume, or lower the temperature.

SPECIFICALLY for shielding gas, I would imagine there is a lookup table - most liquefied gasses at room temperature are in the thousands of psi range. ~3000

Anyone care to elaborate for me? I don't want to re-learn high school stuff that I intentionally forgot a long time ago :D