kt5000
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Tech grade HCl impurities
I grabbed a couple gallons of 31% HCl, labeled muriatic acid, from the hardware store. I call it tech grade because it's intended for swimming pools
and has a bright yellow tint, which I'm guessing is a sulfur compound.
So I'm wondering what is the impurity, and how might I separate the two? Wikipedia notes that HCl was historically produced by mixing sulfuric acid
with a common salt. It also mentions that HCl (aq) is produced as a byproduct of some industrial processes that release HCl gas--but that would
result in a pure HCl solution.
So I'm thinking the H2SO4 + ?Cl --> HCL + ? route must have been used. Can anyone point me to a description of that process? I'm wondering if it
may be possible to simply distill out that impurity 
Thanks!
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kt5000
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Found it, just after posting Looks like it's called the Mannheim process:
2NaCl + H2SO4 --> Na2SO4 + 2HCl
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kt5000
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It doesn't sound like Na2SO4 can be yellow, though.. So I'm still stumped.
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Texium
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The impurity is most likely caused by dissolved iron compounds. Distilling it would still work though.
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Brain&Force
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Really easy method of purifying HCl:
<iframe sandbox width="560" height="315" src="//www.youtube.com/embed/jv1Ms6Subg4?list=UUHdzE4-oN3671525xEuLWCg" frameborder="0"
allowfullscreen></iframe>
At the end of the day, simulating atoms doesn't beat working with the real things...
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kt5000
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Done it With the same guy's video. But it results in a 15.5% HCl solution,
wastes half the HCl, and takes forever to purify any meaningful amount.
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kt5000
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Quote: Originally posted by zts16  | | The impurity is most likely caused by dissolved iron compounds. Distilling it would still work though. |
I'll set up a distillation tonight and see what I can do
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arkoma
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| Quote: Originally posted by kt5000 | Found it, just after posting Looks like it's called the Mannheim process:
2NaCl + H2SO4 --> Na2SO4 + 2HCl |
This gives you GASEOUS HCl. "Liquid Fire" drain cleaner, and non-iodized salt. Bubble through distilled water. Possible EXTREMELY dangerous fumes.
Don't just idly do this without research UTFSE
http://www.sciencemadness.org/talk/viewthread.php?tid=12605
http://www.sciencemadness.org/talk/viewthread.php?tid=22972
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Zyklon-A
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It gives a solution if the acid I'd less than ~90%, contaminated with sodium and sulfate ions of course.
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kt5000
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I started the distillation.. There appears to be a crap level of quality control on this stuff. The impurities are going to be there, and I'm not
worried about that. But the acid concentration seems to vary significantly. The jug I bought a year ago would fume furiously at room temp. The jug
I bought last week doesn't fume at all. Both were listed at approx 31.5% HCl and both were sealed jugs.
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Texium
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I have a gallon of 31.45% hardware store HCl, and fortunately for me it's almost completely clear. If you look at it really closely in the right light
it has a tiny bit of a greenish tint to it, but really barely anything. Guess I just got lucky.
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kt5000
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| Quote: Originally posted by zts16 | | I have a gallon of 31.45% hardware store HCl, and fortunately for me it's almost completely clear. If you look at it really closely in the right light
it has a tiny bit of a greenish tint to it, but really barely anything. Guess I just got lucky. |
Ah, when you said 31.45% it clicked.. My previous acid was 31.45%. I just looked at these bottles, and they're showing 29.00%.
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kt5000
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| Quote: Originally posted by zts16 | | The impurity is most likely caused by dissolved iron compounds. Distilling it would still work though. |
Distilling it appears to work, thanks for the advice 
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arkoma
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I might be drunk, but the HCl gas dissolved in water (hydrochloric acid) is pretty volatile..............
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confused
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agreed, wouldnt the HCL vapor just escape upon heating?
http://en.wikipedia.org/wiki/Solubility_table#H
would it be possible to bubble the resultant HCL gas into ice water, increasing the concentration?
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hyfalcon
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HCl forms an azotrope with water. I don't think you can get it any more concentrated then that.
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arkoma
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| Quote: | II. According to Honigschmid, very pure aqueous solutions of HCl
can be obtained by diluting pure laboratory hydrochloric acid to
20% with water, boiling it with small amounts of KMnO4 to remove
bromine and iodine, and then distilling it through a quartz con-
denser. If the purified hydrochloric acid prepared in this way is
needed in more concentrated form, HCl gas is generated from this
dilute solution with H2SO4 according to the method given under I,
and this product gas is then bubbled through purified 20% hydro-
chloric acid until the latter becomes saturated.
Solubility in water: 1 vol. (15°C) dissolves about 450 vol. of HCl
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Handbook of Preparative Inorganic Chemistry (SciMad Library)
Having had need of *ahem* HCl gas in the 80's, I have a lot of respect for it--it will eat your lungs, burn your eyes out of your head, bleach fabric
and cause every metal object in your house to corrode. The stuff was used as a chemical weapon in WW1.
"We believe the knowledge and cultural heritage of mankind should be accessible to all people around the world, regardless of their wealth, social
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blogfast25
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| Quote: Originally posted by arkoma | | Having had need of *ahem* HCl gas in the 80's, I have a lot of respect for it--it will eat your lungs, burn your eyes out of your head, bleach fabric
and cause every metal object in your house to corrode. The stuff was used as a chemical weapon in WW1. |
Not directly. Decomposition of phosgene and mustard gas does produce HCl, which is responsible for some of the physiological effects of these war
gasses.
Of course you have to be careful around fuming HCl or HCl gas but it's fairly easy to use this chemical safely and responsibly.
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woelen
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HCl can be nasty, but it is not an extremely dangerous gas. I work with 36% HCl fairly comfortably. It does fume and these fumes should not be
inhaled, but it also has good warning properties. These fumes are annoying though. They make every metal object in the neighborhood rust like hell.
I spilled conc. HCl on my skin many times (when working with conc. HCl I do not use gloves), but never had any issues with that. I just rinse the
stuff from my skin with a lot of water, but even if this takes 10 seconds, no real harm is done. It does not burn your skin immediately. Of course,
you should not allow it to remain on your skin for minutes. If you get it on your skin, stay calm and simply rinse away with some water. Conc. HNO3
(60% or so) and conc. H2SO4 (90% or more) are much worse on skin. These very quickly cause serious chemical burns and if you get one of these on your
skin you have to be damn fast in removing it.
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vmelkon
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I have used an allihn condenser when I distilled my hardware store HCl. I had pools of water in each bulge of the condenser. As the HCl dissolved, I
could see the refractive effect.
I have also bought very clear hardware store HCl 1 year later. So quality varies by company.
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Loptr
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| Quote: Originally posted by arkoma | | Having had need of *ahem* HCl gas in the 80's, I have a lot of respect for it--it will eat your lungs, burn your eyes out of your head, bleach fabric
and cause every metal object in your house to corrode. The stuff was used as a chemical weapon in WW1. |
I have accidentally gassed myself with HCL a few times before. You start to notice that it is all around you when the sweat on your brow starts to
burn as it forms hydrochloric acid. Other than that, and your lungs feeling a little sore, it's not something to be paranoid about.
(I had the brilliant idea to attempt to concentrate hardware hydrochloric acid via boiling off water--I was much younger)
[Edited on 21-8-2014 by Loptr]
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careysub
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| Quote: Originally posted by blogfast25 | ...
Not directly. Decomposition of phosgene and mustard gas does produce HCl, which is responsible for some of the physiological effects of these war
gasses.
... |
No, not really. You can find lots of claims to this effect in the historical literature, they are simply repeating WWI-era theories about the effects
(which will probably keep being repeated for the next century).
Both phosgene and the various mustards react directly with functional groups involved in cellular metabolic processes, causing the processes to go
haywire, leading ultimately to cell death.
Rather than being caused by HCl produced by hydrolysis, the hydrolysis in a sense is a detoxification reaction, much good it does the victims
(although the fact that most hydrolysis resistant mustards are the most toxic may indicate that there is a real benefit there).
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