UserPrevKnownAsVanta
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Chloroform & Cu2+ Storage
Hey folks, sorry for dedicating a whole thread to one simple question.
This is why I prefer fora like the chans, everything is disposable.
Anyway.
I want to store a mix of chloroform and copper(II) ions, among other things in a nice looking clear vial.
I've collected many glass storage containers, also plastic ones, but I'm afraid them can't hold both components.
Either the cap, or the insides of the cap really, is made of plastic which might dissolve in the chloroform.
Or the inside of the cap is made from what looks like to be a protective layer of aluminium, which will react with the copper ions.
Does anyone know of a way to store both, simultaneously?
Preferably an easy way.
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JJay
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Use a PTFE-lined cap.
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MrHomeScientist
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Or stretch a piece of PTFE plumbers tape across the mouth of the vial, then wrap some around the threads. Teflon-lined caps can sometimes be tough to
find.
Short questions like this can be addressed to the Short Questions Thread if you really don't want to start a new thread.
Knowledge isn't disposable.
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UserPrevKnownAsVanta
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Thanks lads, I'm not sure I can find PTFE caps (with vials) very easily, but teflon tape should be ok.
I've heard they come in varying thicknesses, I suppose too thick of a wrap and the cap won't fit.
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UserPrevKnownAsVanta
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Hold on, are you the same HomeScientist I accused of having a watermelon fetish?
(And rightly so.)
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anewsoul
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You're probably thinking of TheBackyardScientist.
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UserPrevKnownAsVanta
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Ah yes, you're the other guy.
With the elemental boron.
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UserPrevKnownAsVanta
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https://www.aliexpress.com/item/2ML-lab-vial-glass-bottle-wi...
Aliexpress lists this item as having PTFE caps, or rubbers.
The round circly thingies look very similar to the ones in the OP.
Is there a way to test it they are actually PTFE?
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DraconicAcid
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How is copper(II) mixed with chloroform?
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Amos
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The scintillation vial on the right will definitely work fine for chloroform, just pry out that aluminium liner with a knife or spatula if you're
worried about copper. The one on the right looks like it will too. I work with a lot of different kinds of fragrance and dram vials at work and very
few of them seem to be readily attacked by chloroform. Would I recommend storing the container upside down? Perhaps not, but I don't see why you
would.
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MrHomeScientist
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I mean, I like watermelon just as much as the next guy. But fetish? That may be pushing it a little too far 
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UserPrevKnownAsVanta
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Quote: Originally posted by Amos  | | The scintillation vial on the right will definitely work fine for chloroform, just pry out that aluminium liner with a knife or spatula if you're
worried about copper. The one on the right looks like it will too. I work with a lot of different kinds of fragrance and dram vials at work and very
few of them seem to be readily attacked by chloroform. Would I recommend storing the container upside down? Perhaps not, but I don't see why you
would. |
I actually liked the aluminium(?) layer as it would protect the plastic from the chloroform.
But the copper is a problem.
I'm am myself not too fond of the vial on the left as the cap is actually two parts.
A plasticy (PTFE?) round slab that fits into a black plastic cap with a hole.
I'm pretty sure one of these vials I had filled is already half empty.
They are perfect for solids, but I don't trust them with volatile liquids.
That said, the nice vial on the right with the shiny foil, I only have on of those.
I might just have taken one home from the university lab.
You can't find vials that nice on ebay or Aliexpress.
So I'm not taking out the foil, too risky, what if it leaves a small gap when screwed tight.
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UserPrevKnownAsVanta
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I mean you're not filming yourself shooting a hot load of molten aluminium into those red fleshy fruits of summer.
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UserPrevKnownAsVanta
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I made a mystery 'dye' that does not dissolve in water using only very very amateur chemistry.  Its nice blue/green color comes from copper.
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BasketaneCase
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I'm a little concerned that no-one's mentioned the fact that a clear container means that the Chloroform will definitely decompose to Phosgene, and
that's a bad thing.
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Elemental Phosphorus
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The container should just be stored out of light, or covered in aluminum foil, and add 1% of ethanol to stabilize against the formation of phosgene.
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AJKOER
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See this old thread http://www.sciencemadness.org/talk/viewthread.php?tid=252 .
Relevant comments contained therein include:
"I know that chloroform degrades spontaneously over time to form COCl2." by Polverone
Also:
"in Mario Sartori's "The War Gases Chemistry and Analysis". Sartori does also mention another interesting method:
Quote: In the laboratory, phosgene may be easily prepared be treating chloroform with chromic acid mixture:
2 CHCl3 + 3 O --> 2 COCl2 + H2O + Cl2
By this method the product is impure with chlorine and chloroform (5% about)" from Rahdon's thread.
-----------------------------
I would strongly advise not to employ Aluminum foil, especially extra strength, as it is an alloy of Al/Fe. While, the Al foil is usually passified
by annealing and even a thin acrylic layer, the CHCl3 should remove it. In the presence of water vapor and any O2, possible decomposition of the CHCl3
via an Al/Fe galvanic couple (or, light exposure producing products that enable the galvanic reaction) as follows (assuming no ethanol addition) per
my speculation:
Al/Fe Galvanic Couple ---> e-
e- + nH2O ---> e-(aq)
H2O = H+ + OH-
H+ + e-(aq) ---> .H
.H + O2 + M ---> M + .HO2 (as an aerosol)
.HO2 + CHCl3 --?--> H2O + COCl2 + .Cl
.Cl + .Cl ---> Cl2
....Other products (HCl, .CCl3, CCl4,...)
Note, my suggested products of the last two reactions match the cited reaction above:
"2 CHCl3 + 3 O --> 2 COCl2 + H2O + Cl2"
Or, one could just accept Polverone comment.
----------------------------------------------
Did find a reference that explains how photo active metal oxides, like MgO, in the presence of O2, light and H2O (producing solvated electrons and
hydroxyl radicals), can result in decomposition of CHCl3 to COCl2 (or written as CCl2O). Referenced reactions per Table 4:
G57 CHCl3 +.OH + O2 → CCl3O2 + H2O
G85 CCl3O2 + .HO2 → CCl2O + HOCl + O2
G88 CCl3O2 + CCl3O2 → 2 CCl3O + O2
Note e: CCl3O → CCl2O + .Cl
G58 CHCl3 + .Cl + O2 → CCl3O2 + HCl
Source: "A global model of tropospheric chlorine chemistry: Organic versus inorganic sources and impact on methane oxidation", by Ryan Hossaini, et
al, link: http://onlinelibrary.wiley.com/doi/10.1002/2016JD025756/full
[Edited on 29-4-2017 by AJKOER]
[Edited on 29-4-2017 by AJKOER]
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UserPrevKnownAsVanta
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Okay, so no direct contact with aluminium because of weird redox reactions.
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Elemental Phosphorus
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I meant to use the aluminum foil on the outside of the bottle to shield it from light. In a bottle with a tight Teflon cap there should be no leakage.
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Amos
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I've got a few dozen of the exact same scintillation vials; chloroform will not appreciably damage the lids even over a long period of time. I know
because my uni lab stored chloroform, hexafluoroisopropanol, THF, pyridine, you name it in those vials.
Also, the primary fear of phosgene formation in someone's chloroform shouldn't be one of safety; it should be one of purity. The idea that a
scintillation vial full of chloroform will somehow generate AND store a harmful quantity of phosgene in between openings with such a small volume of
solvent and so little headroom is laughable.
[Edited on 5-1-2017 by Amos]
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Texium
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Thread Moved
18-5-2017 at 08:46 |
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