Consider the 100-L Dewar (a rigid double-walled vessel for storing cryogenic liquids). The Dewar contains nitrogen at 1 atm, 90% liquid and 10% vapor by volume. The insulation holds heat transfer into the Dewar from the ambient to a very low rate, 5 J/s. The vent valve is accidentally closed so that the pressure inside slowly rises. How long time will it take to reach a pressure of 500 kPa?