nitrogen

Answer

Dear Pascal,

Indeed, the temperature of the liquid nitrogen will rise, basically until it has reached the temperature outside the vessel. I assume that the special vessel is heat permeable and is therefore not a “thermos”.

But it’s a bit more complicated because the liquid nitrogen will vaporize once the boiling temperature is reached. Dinitrogen is now converted from liquid to gaseous state. Due to this conversion to gaseous state, the pressure will increase (we can model nitrogen gas well with the ideal gas law: pV = nRT). The pressure in the vessel (p) will therefore be more or less proportional to the temperature T (the pressure will increase slightly more than the temperature because gas molecules are also added from the evaporation process).

At a higher pressure, however, the buying point will increase. Heat must now be added again to get the whole thing back to the boiling temperature. Then liquid nitrogen is again converted to nitrogen gas and the whole process continues to repeat until all liquid nitrogen has been converted to nitrogen gas.

The nitrogen gas can then be heated up further.

Keep in mind that the pressure will be enormous. What I describe above is only possible because we have assumed that the vessel can withstand arbitrarily high pressure! In practice, the barrel has already exploded by now. So don’t try it yourself… 🙂

Kind regards,

Philippe Tassin
Researcher – Free University of Brussels