pichoro - 7-4-2014 at 18:19
Hello. I'm seeking advice on interesting uses of liquid nitrogen, especially that could be converted to educational labs or demonstrations.
Stuff I know you can do:
- Freeze and Shatter Various Materials, such as Roses or Latex Gloves
- Turn a Banana to a Hammer
- Carefully Spray it Using a Rubber Tube
- Superconductors
- Make Ice Cream
- Demonstrate the Leidenfrost Effect
- All Manners of Abuse Involving Ping Pong Balls
This stuff was all fun to do, but now, I'm wondering what else I can do with it. Any proper educational labs? Does it react with anything?
Anyone have any ideas?
MrHomeScientist - 8-4-2014 at 05:56
Lithium is one of the few elements to react with nitrogen under standard conditions, so I wonder what would happen if you dipped a clean piece of Li
into liquid nitrogen? Would it be too cold to do anything, or would it instantly blacken?
bahamuth - 8-4-2014 at 10:24
-Demonstrate thermochromism of LEDs.
-Condense air/oxygen.
-Acetone or alcohol snow.
Zyklon-A - 8-4-2014 at 10:32
I've been wondering, could you condensed pure liquid oxygen from just air in LN2? Because, if the LN2 is at it's
boiling point, it wouldn't really condense more N2 right? Try distilling water with the condenser jacket at 99°C, you'll get almost
nothing.
blogfast25 - 8-4-2014 at 12:07
O2 (l): BP = -183 C
N2 (l): BP = - 196 C
If you led ambient air through a cooling coil in liquid nitrogen, you would cool down the air, ‘in theory’ down to – 196 C, prior to which point
liquid O2 would have condensed out. Of course all the enthalpy you extract from the cooling air is transferred on to the liquid nitrogen and since it
is already boiling, this causes more nitrogen to be blown off: the enthalpy is used as latent heat of vaporisation.
In essence that’s what happens when liquid air is distilled: as the nitrogen distils off, liquid oxygen is left behind.
[Edited on 8-4-2014 by blogfast25]
ScienceSquirrel - 8-4-2014 at 15:07
If you put some liquid nitrogen in a dewar and let it evaporate it gradually accumulates liquid oxygen.
A lit cigarette dipped below the surface will continue to burn.
Liquid nitrogen in a foam cup, left to evaporate and continually topped up can become pale blue as it concentrates liquid oxygen.
A liquid rich in oxygen could be useful for some great demonstrations but it coud be a hazard.
HgDinis25 - 8-4-2014 at 15:13
You could condense oxygen and make a small quantity of oxygen. You could then burn a Diamond in it 
Search around and you'll find awsome info on this topic.
Chemosynthesis - 8-4-2014 at 16:04
Liquid oxygen is interesting. It's neat how something so clear can become blue with a changed index of refraction in a different phase. Definitely
be careful with liquid oxygen and any kind of organic fumes.
Zyklon-A - 8-4-2014 at 17:12
How about this?
vmelkon - 11-4-2014 at 13:23
I have always wondered if it is possible to use LN2 to get some Hg from fluorescent tubes. Just dip one end in and wait a long while. Then break it
open and see if there is a small droplets of Hg.
Another thing to try is, would the fluorescent tube work if the Hg is frozen? I wish they made tubes with no fluorescent powder. I guess they exist
but you won't find it at stores.
LN2 makes a good source of dry nitrogen. (inert atmosphere).
I would definitely use it to make some oxygen. I would use it for my torch.
I would also like to experiment with LO2 (LOX?). Throw in some alkali metals and alkali earth metals.
[Edited on 11-4-2014 by vmelkon]
dontasker - 12-4-2014 at 04:03
As for oxygen condensation:
http://www.periodicvideos.com/videos/008.htm
Good demo of it.
I recall someone doing some demos with liquid nitrogen at my elementary school years ago. They did your standard things like the banana hammer,
freezing a flower and smashing it, also smashed a rubber ball. The one thing that really stood out was putting marshmallows in it and then handing
them out as a treat. They were crunchy, but quickly softened and didn't have the thermal mass to freeze your tongue.
I have a dewar and have filled it up on occasion (welding supply company I'd fill it at closed and I haven't really had a need to try and find another
source), but have not attempted anything beyond reducing conductivity of some electromagnetic coils, making lots of fog, and pouring it out onto a
driveway.