Say I have a gas cylinder with nitrous oxide and cool it down to −78 °C with dry ice. Is there an endothermic process/reaction that would extract the remaining heat from $\ce{N2O}$ and bring it down by 10 °C to its boiling point of −88 °C? I know this could be done by using cryogenics like liquid nitrogen, but I want to avoid those.

  • $\begingroup$ you could let out a little bit of the gas the pressure drops and it cools down $\endgroup$
    – Francis L.
    Mar 28 at 1:30
  • 1
    $\begingroup$ At -78C the N2O vapor pressure is only 1.8 bar - do you think it would be enough just to let that out? $\endgroup$
    – Kozuch
    Mar 28 at 1:40
  • 2
    $\begingroup$ a dry ice/ether cooling bath will get you below -90C $\endgroup$
    – Waylander
    Mar 28 at 6:15
  • $\begingroup$ When dealing with pressurised gases, it is usually better to let the gas flow into a cold place rather than cooling the cylinder. Not least because the gas will still have enough pressure to get out of the cylinder. $\endgroup$
    – matt_black
    Mar 29 at 14:23

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