Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: DoubleWhopper on March 30, 2011, 03:44:10 PM
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Hello,
I was wondering how to turn liquid nitrogen into gas state, i know i should heat it up but i want to have a container with the highest possible nitrogen density and supply in gas state, so when i use the gas it gets replaced by more of the same density.
What do you think about something like this?
Sorry for the double post but i think i posted the other one in the wrong section, please delete it.
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please please please help me i need this project finished for friday and still havent figured it out :'(
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What you have drawn is a bomb. You just need a pressure regulator that maintains a constant internal pressure. I.e. a standard liquid nitrogen tank designed for gas output.
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Lol a bomb!! ;D
well i dont have money to buy one of those tanks, is there any way to make one with cheap stuff or something i may find in my house? ::)
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no
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I am not joking. It really is a bomb. Do not heat liquid nitrogen in any closed container!
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okay i got it its a bomb lol
Please guys help me out i just can get my hands on the liquid form of nitrogen, while i need it in gas state, i need to find a way to do it before friday and my closest attempt its a bomb ::)
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It is going to naturally turn from liquid to gas, do you just need/want a stream of gas or do you really need a specific pressure?
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i have it in liquid form and i need it in gas state, but i cant waste it, and i need it with the most possible purity, i cant mix it with air ::)
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"how" do you have it? I assume it is already in a cylinder?
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i have it in something like this
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fwww.housewaresandbeyond.com%2Fimages%2Fitems%2F11838%2Fjpg%2FThermos-230001C-Stainless-Steel-Insulated-Food-Jar--24-oz.jpg&hash=a8dbc826bcb724fe9283f9b9af3cd9fe4b8475f5)
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I assume the cap screws on
okay, the simplest way: but BE CAREFUL WITH LIQUID NITROGEN
make a secondary container around it; a plastic bag will do, just make sure it is completely sealed with a small valve sticking out of it.
keep the thermos closed for now ("just closed, so that a small twist will open it)
attache a vacuum cleaner to the valve and seal the bag vacuum around the thermos.
close the valve, disconnect the vacuum.
then open the thermos slightly, the liquid nitrogen should evaporate quickly so be ready to close the thermos again.
the gas filling your bag now is pure nitrogen. you can use this by opening the valve in your bag.
under no circumstances heat the thermos can!
if you are very afraid of oxygen content you can pre-load copper filings in the bag before, they may reduce the amount of oxygen present by oxidation of the metallic copper. Just be careful not to puncture the plastic bag.
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NVM i got it... ;D
So if i put some pieces of copper inside the red bag of my drawing the gas will less likely be contaminated with oxygen?
I need a steady supply of pure nitrogen gas over time, maybe i could regulate that with the thermos cap, how much volume of pure nitrogen gas i can get from 1lt of L2N?
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yes, your drawing shows the right idea. after you empty the bag of air around the vacuum, close the valve and slowly open the thermos to inflate the bag.
the volume you can calculate yourself using the density of liquid nitrogen / molar mass, then the gas law.
you would be able to regulate a little with the valve, I would keep the thermos closed for as much as you can, but yeah, you could add some volume to the bag when needed.
sorry I cannot be online more after this message, but I have to run
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I would keep the thermos closed for as much as you can, but yeah, you could add some volume to the bag when needed.
Why would you keep it closed? and how could i add volume to the bag without wasting the N inside of it? ill be using it anyways but im a bit worried about spending all the N inside the bag, and when i need more ill have to wait for it to evaporate and i dont know how much time could it take to fill the bag again....
Could you help me with the math of the gas law/density/molar mass?
is there any way to estimate (or to speed up) the time it will take to fill the bag again if i spend all of the N inside of it?
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Why would you keep it closed? and how could i add volume to the bag without wasting the N inside of it? ill be using it anyways but im a bit worried about spending all the N inside the bag, and when i need more ill have to wait for it to evaporate and i dont know how much time could it take to fill the bag again....
it evaporates VERY quickly, so little time to wait to fill it up, so you want to keep it closed in order not to waste much of it.
and even easier, as found on wiki (did not check to see if this is right, you may want to do that yourself): "the liquid to gas expansion ratio of nitrogen is 1:694"
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So in one Thermos of 1L filled with LN2 i have 694L of Pure N in gas state? :D
Thats awesome, then probably 1L will be enough for my experiment :)
I was wondering how much time will take to evaporate all the LN2 into N if i have 1L and its inside the Thermos, i need a steady supply of pure N gas for half an hour or more, and i need to know at what speed it will be converted and how to make it last for 30+ minutes.
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liquid N2 to gaseous N2 is fast. How fast when you open the top? no idea, sorry.
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No problem, thank you for helping me out with my experiment :)
Still have to make some tweaks to the final design but i think its going to work as intended ;)
This would be so easy if i had $1k to get the required equipment.. ::)
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Well everything went out pretty good with the first experiment.
Now i need to spend/turn 1L of LN2 into N2 in 1/2hr-1hr, ive thought about making something like what i've drawn in the first post, but instead of fire, i could put the thermos in a container filled with boiling water or something like a water bath, then attach a valve to the top of it? the thing is i need some pressure now.. ::)
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Do not put the liquid nitrogen in boiling water; see the above comments about bombs.
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Well finally as i didnt get any answers yesterday and i was very... excited with the experiment i did it anyways, i submerged the thermos in boiling water for a long time, i needed some pressure but it was a big failure, i didnt get any constant pressure, only intermittent and very low, while i needed a good constant flow of N2.
Im considering to buy one of those tanks, they are around $400, do you think they will provide a constant supply of N2 if i fill them with LN2?
Do i have to put pressure in them? I really dont know how this works at all...
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You're going to kill yourself. LN2 is going to take a fairly long time to go to gas while in a thermos... because it's in a thermos. To increase the rate at which the LN2 becomes gas, experiment by changing to various less insulating containers, not putting your insulating container in boiling water. Listen to the experienced chemists here (not myself, but the other three posters in this thread).
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if you are going to spend money, it is probably better to just buy a regulator and compressed nitrogen gas cylinder.