[kennymcmack]

I am trying to understand a situation. 

Let's assume I have a container that can handle infinite pressure.  I pour in liquid nitrogen (LN) so that it's filled to the brim and seal it up.  Then set it on a table where the surrounding conditions are 1 atm and 70F.  I know that the LN at -320F will start boiling and the pressure inside will increase.  And I know that eventually it will reach equilibrium and the solution inside will eventually reach 70F.  But how do I calculate that equilibrium pressure?  Will all of the liquid convert to gas before equilibrium?  Or will there be a partial solution of LN and gaseous nitrogen (GN)?

I am looking at the vapor curve from http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=5 and it shows that 70 F (294K) is to the right of the critical point.  It doesn't appear that you can compress gaseous nitrogen to get a liquid. 

So my main question is, if you put liquid nitrogen (or possibly any other cryogen) in a sealed container, what will the pressure rise to if the solution warmed to 70 F?

Thanks, Kenny. 

[kennymcmack]

After some more research, I am learning that it's a super critical fluid over about -234 F and 450 psig.  But how do you still calculate the pressure in this supercritical range?

[billnotgatez]

If we assume the liquid will change from -320F to +70F
Will the volume change if you seal the container.
Will the number of moles change if you sealed the container.
Will the pressure change if you sealed the container.

By the way, be careful with Fahrenheit and psig

[billnotgatez]

from
http://www.airproducts.com/~/media/Files/PDF/company/safetygram-7.pdf

Table 1: Liquid Nitrogen Physical and Chemical Properties
Chemical Formula                                            N₂
Molecular Weight                                            28.01
Boiling Point @ 1 atm                                       –320.5°F (–195.8°C)
Freezing Point @ 1 atm                                      –346.0°F (–210.0°C)
Critical Temperature                                        –232.5°F (–146.9°C)
Critical Pressure                                           492.3 psia (33.5 atm)
Density, Liquid @ BP, 1 atm                                 50.45 lb/scf
Density, Gas @ 68°F (20°C), 1 atm                           0.0725 lb/scf
Specific Gravity, Gas (air=1) @ 68°F (20°C), 1 atm          0.967
Specific Gravity, Liquid (water=1) @ 68°F (20°C), 1 atm     0.808
Specific Volume @ 68°F (20°C), 1 atm                        13.80 scf/lb
Latent Heat of Vaporization                                 2,399 Btu/lb mole
Expansion Ratio, Liquid to Gas, BP to 68°F (20°C)           1 to 694

[kennymcmack]

Thanks for the info Bill. 

Yes temp goes from -320 F to +70 F
No the volume will be constant once the container is sealed
The number of moles will be constant throughout the process
Yes the pressure will definitely increase.

Thanks for the note. 

Kenny.