How come nitrogen can stay so cold in all temperatures? I guess it’s not cold when compressed inside the bottle, rather a reaction when turning to gas? But where does the energy from the “room temperature” go?
In: Chemistry
> Sorry. If you keep a container of compresses nitrogen in the backing sun for 5 hours and then open it and pour it on your face, your face will get cold. Why is your face cold?
DO NOT EVER DO THIS! (Unless you know what you’re doing)
Liquid Nitrogen is dangerous, and should be handled with care. You don’t just leave a random compressed liquid nitrogen container baking in the sun. There is a real risk of it exploding and hurting people and destroying property.
> I guess it’s not cold when compressed inside the bottle, rather a reaction when turning to gas?
It is COLD! I think you are thinking about the lots of online videos when people are pouring liquid nitrogen into stuff, or dipping stuff into liquid nitrogen and getting to freeze in a snap. In all of these cases, the liquid nitrogen is NOT compressed, and it is COLD.
This is a dangerous substance, please handle it with care. This is why you need a certification / training to handle it, buy it, and transport it. You cannot be in elevator with it, you cannot use the stairs while carrying it. You have to book the elevator, put it in, let it travel to the desired floor alone, have another person there so that no one accidentally goes into the lift. Because you it spills while there’s someone in the elevator, the liquid nitrogen will evaporate, the temperature will drop, and the oxygen will be pushed away, and people will die. Same thing with car. You always put uncompressed liquid nitrogen in the trunk, never in the same area with the passenger. And you also keep it uncompressed. Because the pressure built up will be great, and most containers will explode.
So how does it stays cold? Well, it doesn’t. Just like how you buy a 5kg pack of ice, load it into the car, and after an hour of driving, some have melt, but not completely. The same deal with liquid nitrogen, it is always evaporating to gas. And after a while, it will be gone.
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