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Author: Subject: Making Chlorine
tetrahedron
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[*] posted on 29-11-2012 at 13:30


Quote: Originally posted by elementcollector1  
how did the container containing the dry ice/ethanol mix withstand the temperature? It doesn't look like borosilicate, so unless ordinary soda-lime glass is significantly stronger than I thought, I would expect the container to shatter.

just being at a certain temperature doesn't cause thermal shock, it's the rapid change that does. after adding the dry ice, the ethanol takes a while to cool, so it provides a sort of heat buffer in the meantime. also, the relatively hot gas doesn't carry enough heat to cause a dangerous shock. consider it a sort of distillation, just carried out at room temperature rather than at the boiling point of water/ethanol/...
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watson.fawkes
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[*] posted on 29-11-2012 at 14:34


Quote: Originally posted by MrHomeScientist  
Would those really hold enough pressure to keep chlorine liquid? I thought they were too thin-walled for that.
Those are preformed ampoules. An ampoule as such doesn't need to be preformed. Many of the pre-formed ones are flint glass, as borosilicate would be overkill. I mentioned borosilicate because it's much easier to find dimensional tubing in borosilicate rather than flint glass.

The short answer to your question is that I don't know. 8 bar is only about 120 psi, though. That's well within the range of a typical shop compressor. So test one to destruction with compressor air. Make jig, clamp on a hose, and use stops to prevent the ampoule becoming a bullet. Bring it up to pressure behind a blast shield. If it's not broken yet, tap on it and see if it breaks.
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[*] posted on 29-11-2012 at 15:01


..or store it in the freezer (<2 bar should be manageable). any leak will help preserve your food ;p
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elementcollector1
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[*] posted on 29-11-2012 at 16:56


Quote: Originally posted by tetrahedron  
..or store it in the freezer (<2 bar should be manageable). any leak will help preserve your food ;p

...I'd rather not.
I use disposable glass pipettes as ampoules, instead of those official things.
So, once I've put in a minimal amount of liquid chlorine into my ampoule and sealed it, anything fun to do with the rest?




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[*] posted on 30-11-2012 at 00:44


Quote: Originally posted by elementcollector1  
anything fun to do with the rest?

i'd make some anhydrous metal chlorides with it.
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MrHomeScientist
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[*] posted on 30-11-2012 at 06:28


Quote: Originally posted by watson.fawkes  
Those are preformed ampoules. An ampoule as such doesn't need to be preformed. Many of the pre-formed ones are flint glass, as borosilicate would be overkill. I mentioned borosilicate because it's much easier to find dimensional tubing in borosilicate rather than flint glass.

The short answer to your question is that I don't know. 8 bar is only about 120 psi, though. That's well within the range of a typical shop compressor. So test one to destruction with compressor air. Make jig, clamp on a hose, and use stops to prevent the ampoule becoming a bullet. Bring it up to pressure behind a blast shield. If it's not broken yet, tap on it and see if it breaks.


I do have some tiny test tubes I have used as ampoules before, but I'm not sure if those are borosilicate. I don't suppose there's any way to tell? They are pretty thin-walled though. I think in the end if I want to store the liquid for display I'll cast the ampoule in resin - that's how I've seen some display samples of bromine sold and it would let me sleep better at night I think :) In the meantime I'll proceed with my original plan to ampoule only the gas. Woelen's method sounded pretty good too.

The pressure test is a very interesting idea, as long as all those safety measures are in place. It would probably be a good idea to put the whole thing in a box too so I don't end up with glass shards everywhere. That would make an exciting video too I think!
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elementcollector1
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[*] posted on 30-11-2012 at 08:55


Quote: Originally posted by tetrahedron  
Quote: Originally posted by elementcollector1  
anything fun to do with the rest?

i'd make some anhydrous metal chlorides with it.


Sounds fun, how do I start? I'd probably have a flask of liquid chlorine, leading to a flask of a metal, allow the liquid chlorine to warm up to room temperature...
I seem to have noticed that if you look at the 'lip' of the glass, borosilicate and soda-lime seem to be different colors. Soda-glass seems to be more blue, and borosilicate closer to yellow or yellow-green. This may be something else, however.




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[*] posted on 21-3-2014 at 08:25
HCl Electrolysis


Lately i've been looking for a way to produce chlorine gas that I could start and stop at will.

I settled on electrolysis of HCl, as it has a long term reliable output.
Im using graphite anodes, and a old computer powersupply. My anode surface area is 4in2. The power supply outputs 12A @ 3v, 12A @ 5v and 16A at 12v. So a current density of 3-4A/in2 Ive been experimenting with different voltages, the largest production is at 12v, 3v and 5v visually produce the roughly the same amount of gas. I think with increasing voltages more side reactions are likely to occur (More O2 production, higher anode erosion-likely CO and CO2).

I have a few questions though. There must be some oxygen produced as well as chlorine right? What conditions favor chlorine production? Is it possible free chlorine is combining with the carbon, or carbon-oxygen compounds forming things like CCL4, or Phosgene?




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[*] posted on 21-3-2014 at 09:16


Quote: Originally posted by I Like Dots  
Lately i've been looking for a way to produce chlorine gas that I could start and stop at will.

I settled on electrolysis of HCl, as it has a long term reliable output.
Im using graphite anodes, and a old computer powersupply. My anode surface area is 4in2. The power supply outputs 12A @ 3v, 12A @ 5v and 16A at 12v. So a current density of 3-4A/in2 Ive been experimenting with different voltages, the largest production is at 12v, 3v and 5v visually produce the roughly the same amount of gas. I think with increasing voltages more side reactions are likely to occur (More O2 production, higher anode erosion-likely CO and CO2).

I have a few questions though. There must be some oxygen produced as well as chlorine right? What conditions favor chlorine production? Is it possible free chlorine is combining with the carbon, or carbon-oxygen compounds forming things like CCL4, or Phosgene?


First instead of precious HCl why not use more readily available NaCl
and acetic acid to keep the pH low. Some oxygen is generally produced.
Chlorine production is favored by low pH among other things like
electrode material. Yes, the carbon will react with the chlorine slowly
destroying your electrode. The side products are going to depend a
lot on your current density and the density of your electrode.
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[*] posted on 21-3-2014 at 09:26


A two neck flask... Crushed TCCA in the flask, a pressure equalized addition funnel with 15% or so HCl in one neck, and in the other neck a take off adapter with tube going to wherever you want the chlorine. Just add the HCl and stop adding it to stop generating chlorine.
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[*] posted on 21-3-2014 at 11:40


A [url=http://en.wikipedia.org/wiki/Kipp's_apparatus]Kipp generator[/url] is also a nifty way to generate gases on-demand. The page conveniently mentions a method for chlorine with the device - HCl and MnO2 or KMnO4.

[Edited on 3-21-2014 by MrHomeScientist]

Hrm, suddenly url tags don't work?

[Edited on 3-21-2014 by MrHomeScientist]
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[*] posted on 21-3-2014 at 14:03


Quote: Originally posted by macckone  
First instead of precious HCl why not use more readily available NaCl
and acetic acid to keep the pH low. Some oxygen is generally produced.
Chlorine production is favored by low pH among other things like
electrode material. Yes, the carbon will react with the chlorine slowly
destroying your electrode. The side products are going to depend a
lot on your current density and the density of your electrode.


Does this really work to produce chlorine? I can obtain 10% acetic acid solution, which I could saturate with NaCl. Obviously this would form sodium acetate as a byproduct.
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[*] posted on 21-3-2014 at 14:38


It does, but the product is contaminated with oxygen.



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[*] posted on 21-3-2014 at 15:03


Well it doesn't matter in my case. :) I think Im gonna test this ASAP and post results. I'm gonna need to reinstall my graphite electrodes though, it'll take some time.

Oh by the way, is the oxygen produced in the cathode compartment? Because I can separate the electrodes by encapsulating them into separate floating tubes.
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[*] posted on 21-3-2014 at 15:19


Nope, anode along with the chlorine. Hydrogen is produced at the cathode.



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[*] posted on 21-3-2014 at 16:41


Quote: Originally posted by Mailinmypocket  
A two neck flask... Crushed TCCA in the flask, a pressure equalized addition funnel with 15% or so HCl in one neck, and in the other neck a take off adapter with tube going to wherever you want the chlorine. Just add the HCl and stop adding it to stop generating chlorine.



It really needs to not be more complex than this, in fact if you're just collecting the gas for display or on a cold finger a plain addition funnel is fine. I know people don't like reading but len1 also showed that with this method the cacl2 drying tub was redundant.
Likewise I have a post somewhere where I prepared some 500ml of liquid cl2 then transferred this to Lecture bottle.




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[*] posted on 21-3-2014 at 17:44


Quote: Originally posted by Panache  
I prepared some 500ml of liquid cl2 then transferred this to Lecture bottle.


Now that's neat.

As far as HCl electrolysis, I am also interested in the possibility of insitu chlorination. Ex: ethanol / acetone.




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[*] posted on 22-3-2014 at 04:37


I tried acetone. I couldn't get it to work very well, due to tar formation.

http://www.sciencemadness.org/talk/viewthread.php?tid=936&am...

However, my cell was pretty crude, as were my reagents (hardware store grade).

[Edited on 22-3-2014 by Cheddite Cheese]




As below, so above.
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[*] posted on 20-10-2014 at 04:45


Nice to have a forum search engine.

I was debating with myself the relative merits of various methods for creating chlorine --
I have previously done KMnO4 + HCl
I have also done HCl and laundry bleach.
I was curious which was better -- to use HCl and Ca(OCl)2 or HCl and TCCA.

I also had some questions about both vapour and liquid ampouling. Pretty much everything answered here.

I have decided to go for the HCl and TCCA route on the basis that the product is not going to be contaminated with O2 and also because it is less likely to need drying. Can someone confirm that I have this correct?
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