mycotheologist
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Bubbling Cl2 gas
I don't have any glass tubing so I made do with some bunsen burner tubing (which is made of natural rubber if I'm not mistaken). I know this is asking
for trouble but its holding up surprisingly well. Heres an apparatus I used to make some I2 from aqueous KI:
This setup is actually quite safe. I only got a very mild smell of Cl2. I wouldn't use it indoors though, I wouldn't trust my improvised
fume hood to protect me against Cl2 fumes. In the addition funnel, theres this crappy brick and patio cleaner which contains <5% HCl and
non ionic surfactants. In the flask is solid Ca(ClO)2. When I get some glass tubing, I'll never submerge rubber tubing in the reaction
solution like that but I don't see any reason not to use bunsen burner tubing to connect the glass tubing to the reaction flask. It holds up against
HCl and NH3 very well, this is the first time I've tested it with Cl2 though so I'll find out if it reacts with the Cl2 or I2 soon enough.
Heres a video of the apparatus in action:
https://www.youtube.com/watch?v=k7uwqhpU1vE
[Edited on 10-5-2012 by mycotheologist]
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barley81
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Bubbling Cl2 into aqueous KI isn't a very good way to make iodine because iodine monochloride and iodic acid can be formed as well, reducing yield and
introducing contamination. The tetrachloroiodide ion may also be formed (this is golden yellow).
Nice-looking setup though.
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mycotheologist
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Yeah I was just testing it out, the yield of I2 wasn't very good. While using this apparatus outdoors is relatively safe, the dangerous part is
cleaning up. When I was cleaning out the reaction flask I got a strong whiff of Cl2 which gave me a fright. If I'm not mistaken, the damage it causes
is mainly corrosive/oxidative damage so if you are inhaling dangerous amounts of it, you'll know it. From dealing with NH3 and Cl2 I've gained a
healthy fear of insidious gases like CO. I didn't know about these interhalogen compounds, thanks for informing me about that. Thats pretty cool, I
woulda never suspected a compound like ICl existed. I think you're right because at first, the solution turned dark brown but after bubbling enough
Cl2 through it, I ended up with a golden solution with a pile of I2 crystals at the bottom.
UPDATE: The I2 and/or the Cl2 appears to have reacted with the bunsen burner tubing. The outside of the tubing is slowly turning white. The inside of
the tubing didn't change colour and no physical deformation occurred at all so I'm impressed by the tubings resistance to the halogens.
[Edited on 10-5-2012 by mycotheologist]
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AndersHoveland
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In aqueous solution, chlorine can oxidize bromine to bromic acid, and iodine to iodic acid.
I2 + 5 Cl2 + 6 H2O --> 2 HIO3 + 10 HCl (aq)
(note that this reaction is reversible if the acids are concentrated enough)
In the absence of water, iodine reacts with chlorine, at room temperature, to first form ICl, then iodine trichloride. Indeed, the reaction of
concentrated iodic acid with concentrated hydrochloric acid can produce iodine trichloride. "Iodine trichloride" actually exists as the dimer, I2Cl6.
[Edited on 11-5-2012 by AndersHoveland]
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