Isolation of Xenon or Krypton

[silkworm]

Wow, first of all I'd just like to say I'm impressed with the population of this website, it looks very solid.

 

I was wondering if anyone had any ideas on how a poor Kansas boy who lives in his parents basement could isolate some Xenon or Krypton to work with over the holiday break? I guess fractional distillation of air is the only method that can get this, but if that's the method to use are there any suggestions about trapping the air?

 

As to why, I'm interested in experiencing them in solid form. I know that with my limited resources it would be difficult to reach down to 116K with high pressure, but, hopefully, I can figure it out as soon as I get the "stuff." I just can't imagine what these would be like as solids, but their melting points are listed so I thought I'd check it out.

 

Thank you.

[jdurg]

Since Xenon and Krypton are virtually unreactive gases, the only way to obtain them from air is through fractional distillation. There is no chemical way to do it. The concentration of Xenon and Krypton in air is exceedingly low. Thier names arise from the Greek words Xenos (Stranger) and Kryptos (Hidden) due to the fact that these two gases are in such low quantities that early scientists simply could not see them. You need to liquify a LARGE amount of air to get any type of visible amount of Xe or Kr. Once everything is liquified, you would have to remove all of the nitrogen, oxygen, carbon dioxide, neon, helium, and argon from the air. It is simply not possible to do this in one's own home as the sheer size of the equipment you would need to do this is bigger than most people's homes. The only reason why these gases are even available is due to the large demand for liquified oxygen and nitrogen. The companies that produce liquid N2 and O2 deal with such large quantities of air that they actually can produce significant amounts of Xenon and Krypton.

 

I guess it would be kind of like trying to extract gold from a source of gold ore. In order to get any appreciable amount, you'd have to process MASSIVE quantities of ore.

[insane_alien]

you could always buy a canister of xenon and freeze it. (i assume you have the equipment and know-how to achieve these cold temps)

[silkworm]

jdurg:

 

"You need to liquify a LARGE amount of air to get any type of visible amount of Xe or Kr. Once everything is liquified, you would have to remove all of the nitrogen, oxygen, carbon dioxide, neon, helium, and argon from the air. It is simply not possible to do this in one's own home as the sheer size of the equipment you would need to do this is bigger than most people's homes."

 

I was worried about this, but I think I can solve it by engineering something of relatively small volume that can suck up air and allow me to rerelease the stuff I don't want while keeping the stuff I do. I call it, "the ultimate cooler." My only problem there, from a chemistry persective, is overlapping boiling points.

 

Do you have any suggestions on where the best place would be to find xenon and krypton? I mean, radon (which I don't want to use for obvious reasons) has notoriety for collecting in basements. Anything like that? I've been looking for information on this but I'm pretty much internet illiterate anymore and I'm on dialup.

 

insane_alien:

 

"you could always buy a canister of xenon and freeze it."

 

Where's the fun in that? Actually I had no idea it would be commercially available in elemental form. I'm bumping around looking for some now. Hopefully it's not too expensive because I'm basically a fringe homeless science student.

 

"(i assume you have the equipment and know-how to achieve these cold temps)"

 

Nope, but my personal hero is a physics teacher at WSU that does superconductor research with liquid Helium. He built all of his equipment from spare parts around the university and a few hundred bucks in the 70s. I have the concepts down, so hopefully I can engineer something myself.

 

Thank you to you both for your input.

[RyanJ]

I was wondering if anyone had any ideas on how a poor Kansas boy who lives in his parents basement could isolate some Xenon or Krypton to work with over the holiday break? I guess fractional distillation of air is the only method that can get this' date=' but if that's the method to use are there any suggestions about trapping the air?

[/quote']

 

A quote from webelements.com on Xenon:

 

Xenon is present to a small extent in the atmosphere (less than 1 ppm by volume) and is obtained as a byproduct from the liquefaction and separation of air. This would not normally be carried out in the laboratory and xenon is available commercially in cylinders at high pressure.

 

http://www.webelements.com/webelements/elements/text/Xe/key.html

 

And on Krypton:

 

Krypton is present to a small extent (about 1 ppm by volume) in the atmosphere and is obtained as a byproduct from the liquefaction and separation of air. This would not normally be carried out in the laboratory and krypton is available commercially in cylinders at high pressure.

 

http://www.webelements.com/webelements/elements/text/Kr/key.html

 

Unless you have some pretty high tech equiptment you'r not going to be abel to use that method anyway!

 

If you did have access to a lab there are other more compex methods that oen cna use (One involving a centrifuge and one involving something simmilar to a mass specrometer.)

 

Cheers & Good Luck,

 

Ryan Jones

[jdurg]

Heh. You'll pretty much ONLY find Xenon in an elemental form as it doesn't form any stable chemical compounds that you're likely to find. As to where to get it, you can always look for liquified gas companies as they probably have canisters of the gases. I will warn you that a full canister of Xenon or Krypton will cost a pretty penny since those gases are not exactly common, hence a high price. If you do want to try and obtain them yourself from liquid air, I can at least save you SOME research and post the boiling points (In Degrees Celcius) of the noble gases and other gases in air.

 

He: -268.93

Ne: -246.08

N2: -195.79

Ar: -185.80

O2: -182.95

Kr: -153.22

Xe: -108.00

 

So if you liquify a bunch of air, you'll need to go and SLOWLY let it boil away while carefully monitoring the temperature. Once you see that the oxygen gas is boiling off the liquid that is left will be composed of Kr and Xe. I'll warn you, however, that even if you were to liquify massive quantities of air, you may only wind up with a few mL of the Xe/Kr mixture.

[silkworm]

Sorry, I need to learn how to work quotes on this thing.

 

Jdurg:

 

" Heh. You'll pretty much ONLY find Xenon in an elemental form as it doesn't form any stable chemical compounds that you're likely to find."

 

Although I agree that what I said came across as dumb because of its redundancy, but I'd like to refer you to the work Dr. Neil Bartlett who I now understand is at Berkely. He created a few Xe fluorides while at the University of British Columbia. Since then some Xe oxides have also been made and there are some Kr fluorides and perhaps a (very) few others. I don't think any of these have been found in nature though and I doubt any are for sale.

 

About the boiling points, thanks for looking out. I did a little searching myself and was happy to find that the only compound of substantial relative abundance in the atmosphere in between the boiling points of Xe and Kr is ozone. Since purity is an issue, this is a little more of a hassle in engineering, but it's workable.

 

Do you, or anyone else out there, happen to know any good places on the net to find phase diagrams? I find these immensely useful, especially in this case, but I can't find any outside of a few compounds in textbooks.

 

Thanks for the information Ryan J.

[jdurg]

That's why I stated "any stable chemical compounds that you're likely to find". Besides, those Xenon and Krypton compounds aren't exactly 'stable' since they tend to react with everything in existance. So you won't be able to generate your Xe or Kr via chemical means.

 

With the ozone, I wouldn't worry about it. Ozone is INCREDIBLY reactive and will decompose rapidly into oxygen gas as you concentrate the air. (I.E. liquify it).

[silkworm]

jdurg:

 

"That's why I stated "any stable chemical compounds that you're likely to find". Besides, those Xenon and Krypton compounds aren't exactly 'stable' since they tend to react with everything in existance."

 

That depends on your definition of stable. What I use and the way I generally hear it used is that stable refers to the ability for the compound to stay together on its own, reactivity refers to these Xe and Kr fluorides. Highly reactive.

 

"With the ozone, I wouldn't worry about it. Ozone is INCREDIBLY reactive and will decompose rapidly into oxygen gas as you concentrate the air. (I.E. liquify it)."

 

Sweet. Do you know of anywhere I can find a phase diagram for this stuff?

 

By the way, here is my list for the gases below the Karman Line (100km).

 

Cpd: BP (ºC): % Abundance:

H20 100 Variable

NO2 + 21.2 Trace-> 2.0x10-6

SO2 - 10.6 Trace-> 1.0x10-5

NH3 - 33.3 Trace-> 3.0x10-7

CO2 - 78.4 (sublime) 3.50x10-2

N2O -88.6 3.1x10-5

Xe - 108.0 8.7x10-6

O3 - 111.9 Trace-> 8.0x10-4

Kr - 153.2 1.14x10-4

CH4 - 161.4 1.7x10-4

O2 - 182.95 2.0947x101

Ar - 185.8 9.34x10-1

CO - 191.5 Trace-> 2.5x10-5

N2 - 195.8 7.8084x101

Ne - 246.1 1.818x10-3

H2 -253 5.3x10-5

He - 268.9 5.24x10-4

 

I have about 20ºC of space before I hit Xenon then about 8ºC before I have to worry about methane, and that's workable. I have to look at a phase diagram, but I'm worried I'll have to physically remove the CO2 and isolate it from the rest of the bath to keep it from mixing with the Xe and Kr when I distill them. It's been my experience that it doesn't take much pressure at all to keep dry ice from sublimating, so that may be a problem.

 

Gracisimo.

[olmpiad]

The cost of producing Krypton or Xenon would far surpass the cost of buying a few flashlight or camera bulbs. The package says what gas they are filled with.

[Ilja]

jdurg:

 

"You need to liquify a LARGE amount of air to get any type of visible amount of Xe or Kr. Once everything is liquified' date=' you would have to remove all of the nitrogen, oxygen, carbon dioxide, neon, helium, and argon from the air. It is simply not possible to do this in one's own home as the sheer size of the equipment you would need to do this is bigger than most people's homes."

 

I was worried about this, but I think I can solve it by engineering something of relatively small volume that can suck up air and allow me to rerelease the stuff I don't want while keeping the stuff I do. I call it, "the ultimate cooler." My only problem there, from a chemistry persective, is overlapping boiling points.

 

Do you have any suggestions on where the best place would be to find xenon and krypton? I mean, radon (which I don't want to use for obvious reasons) has notoriety for collecting in basements. Anything like that? I've been looking for information on this but I'm pretty much internet illiterate anymore and I'm on dialup.

 

insane_alien:

 

"you could always buy a canister of xenon and freeze it."

 

Where's the fun in that? Actually I had no idea it would be commercially available in elemental form. I'm bumping around looking for some now. Hopefully it's not too expensive because I'm basically a fringe homeless science student.

 

"(i assume you have the equipment and know-how to achieve these cold temps)"

 

Nope, but my personal hero is a physics teacher at WSU that does superconductor research with liquid Helium. He built all of his equipment from spare parts around the university and a few hundred bucks in the 70s. I have the concepts down, so hopefully I can engineer something myself.

 

Thank you to you both for your input.[/quote']

 

You can liquifiy air in fractions so you won't need to remove all the things you don't need.Like Carbon-dioxide will be liquid first and so on...

[RyanJ]

The cost of producing Krypton or Xenon would far surpass the cost of buying a few flashlight or camera bulbs. The package says what gas they are filled with.

 

And if you always need more they sell this stuff in preassureised bottle, if you cna find people who dod a lot of welding or even welding stores you can always ask them if you cna have some.

 

Cheers,

 

Ryan Jones

[jdurg]

You can liquifiy air in fractions so you won't need to remove all the things you don't need.Like Carbon-dioxide will be liquid first and so on...

 

Yes, but because Xenon and Krypton are in such vanishingly small amounts, you won't be able to actually concentrate it. (As the one or two picoliters you get will evaporate readily even if it is kept incredibly cold). You need a large amount of air in order to extract the tiny bits of xenon and kyrpton that are in there. No process is 100% efficient, so you have to have a large amount of substance in order to deal with the fact that some of it will evaporate/boil away.