A sealed, well-insulated 2000mL thermos bottle with negligible heat capacity is completely empty - a perfect vacuum. To this you add 550 mL of liquid nitrogen at its boiling point and a piece of scrap iron of mass 202g initially at a temperature of 239K. Foolishly, the bottle is sealed tightly so that no gas can escape. You then hide the thermos under the professor's lectern, sneak out of the room, and await the inevitable explosion. After a few seconds have passed, what is the pressure inside the thermos? The density of liquid nitrogen is 810 kg/m^3.