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Author: Subject: HCl Preparation with no other strong acid
Texium
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[*] posted on 14-5-2018 at 16:50


Quote: Originally posted by AJKOER  
A modification of the chlorine gas in water approach, starting by heating a copper tube to enrich its oxide coating. Insert the copper tube in the water to which is bubbled Cl2 gas. The water vessel should be ice cooled. Per Wikipedia (https://en.wikipedia.org/wiki/Hypochlorous_acid )
Can you actually TRY that before posting it as if it's fact? It doesn't sound very hard.



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[*] posted on 14-5-2018 at 17:12


Quote: Originally posted by Texium (zts16)  
Quote: Originally posted by AJKOER  
A modification of the chlorine gas in water approach, starting by heating a copper tube to enrich its oxide coating. Insert the copper tube in the water to which is bubbled Cl2 gas. The water vessel should be ice cooled. Per Wikipedia (https://en.wikipedia.org/wiki/Hypochlorous_acid )
Can you actually TRY that before posting it as if it's fact? It doesn't sound very hard.


Why would he break the habit of a lifetime?




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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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AJKOER
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[*] posted on 15-5-2018 at 02:54


Not clear on what am supposed to have performed anew?

On heating the copper tube, I am currently away from home with only access to an electric stove, on which I did not attempt to heat copper metal (like pennies and such).

Now, my prior experience on heating Cu with a methane flame and dropping into water was interesting as I recall discussing previously somewhere. The placing of very hot Cu into water appears to produce red Cu2O. [EDIT] Research of patents, see https://patents.google.com/patent/US2507008 , suggests to me that replacing water with vinegar may produce a higher residual amount of red Cu2O (the CuO being more readily dissolved).

As to the results with a CH4 flame, there is some black CuO formation, but there is also, depending on where the Cu is placed into the methane flame, I suspect the reaction:

Cu2O/CuO + CH4 --> Cu + CO/H2

which is not balanced, and assumed to parallel the much higher temperature reaction reported between Al2O3 and CH4:

Al2O3 + 3 CH4 --> 3 CO + 6 H2 + 2 Al

---------------------------------------------------------------------

I would recommend placing the chlorine generator (with a partial loading to produce limited chlorine gas) in a larger wide mouth glass vessel (sitting on ice) with a heavy glass cover (this would allow for some gas pressure release). The Cl2 generator would be surrounded by water containing pieces of previously heated copper metal forming mixed oxides.
---------------------------------------------------------------------

Now, the 'show me' response of my more esteem colleagues probably relates to the issue of the interplay between chlorine and water:

Cl2 + H2O = HCl + HOCl

Normally, the reaction does not meaningfully appear to move to the right. However, in the presence of CuO:

2 HOCl --CuO--> 2 HCl + O2

3 HOCl --CuO--> 2 HCl + HClO3

So, one may hope that chlorine water equilibrium reaction could move to the right to adjust for the loss of the HOCl. However, the increase in chloride argues otherwise

So, yes, I agree some experimenting, including pH measures, would be insightful.

[Edited on 15-5-2018 by AJKOER]
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[*] posted on 15-5-2018 at 03:40


Yes, methane should be able to reduce copper oxides to the metal, we did this back in school by loading black copper oxide into modified test tubes then heating from underneath with a Bunsen burner whilst pumping methane through the tube.



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[*] posted on 15-5-2018 at 10:16


Free-radical chlorination of hydrocarbons with Cl2 gas and light will produce copious amounts of HCl gas. In that reaction I did in 2010, you can add a catalytic amount of a bromide salt to toluene and bubble chlorine gas into that in the presence of strong light (sunlight works quite well). It produces benzotrichloride eventually (as per Ullmann) which is quite a useful compound. It can be used to produce acyl chlorides, or can be mixed with benzoic acid 1:1 molar to get benzoyl chloride.

Presumably the mechanism is highly selective for benzylic and allylic hydrogens, so other compounds that have hydrogens in that position should presumably work. Though, you probably should avoid propylene.

And best of all, this reaction would give AJKOER a chance to go nuts with a free-radical reaction! ;)




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Texium
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15-5-2018 at 11:09
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[*] posted on 15-5-2018 at 16:46


Quote: Originally posted by AJKOER  
A modification of the chlorine gas in water approach, starting by heating a copper tube to enrich its oxide coating. Insert the copper tube in the water to which is bubbled Cl2 gas. The water vessel should be ice cooled. Per Wikipedia (https://en.wikipedia.org/wiki/Hypochlorous_acid ) and other sources:

"The presence of light or transition metal oxides of copper, nickel, or cobalt accelerates the exothermic decomposition into hydrochloric acid and oxygen:[10]

2 Cl2 + 2 H2O → 4 HCl + O2 "

Actually, per a recent thread comment, in the presence of black CuO, expect some HClO3 as well (see http://www.sciencemadness.org/talk/viewthread.php?tid=81555#... ).
-------------------------------------------------

An interesting way to make Cl2 , without a strong acid, is to add a piece of copper and aluminum metal to a solution of chlorine bleach (NaOCl), a good dose of NaCl and vinegar (research 'bleach battery' on SM, here are some links: http://www.sciencemadness.org/talk/viewthread.php?tid=81796#... and http://www.sciencemadness.org/talk/viewthread.php?tid=81555#... ). Jump start the electrochemical cell in a microwave.

[EDIT] Without the microwave quick start, I actually yesterday did an attempt to expand the bleaching power of HOCl by placing the target fabric in an aluminum pan with chlorine bleach, vinegar and NaCl. To my surprise in under an hour, a micro hole leak in the Al pan became apparent!

[Edited on 14-5-2018 by AJKOER]


You're early, another year and this thread will been a decade old!

All so more other more fresh threads on this.
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[*] posted on 15-5-2018 at 20:51


Quote: Originally posted by entropy51  
Mossydie,

The Golden Book of Chemistry Experiments, easily found by Googling, uses sodium bisulfate instead of sulfuric acid for small scale preps. Bisulfate was a standard chemical used in place of sulfuric acid in the chemistry sets of the good old days.


The Golden Book is in the library. I put it there.




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[*] posted on 15-5-2018 at 22:44


You could probably get dilute hydrochloric acid by combining MgCl2 or CaCl2 with oxalic acid, in solution. Though the purity obviously wouldn't be ideal.



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[*] posted on 15-5-2018 at 23:13


Has that really been proven to work
Cacl2 and oxalic acid to make HCl acid

Same with magnesium sulfate to sulfuric acid

Just because it is that magnesium oxalate is insoluble expected the reaction proceeds forward?

The mystery if a weak acid can percipitate a salt of a weak acid and a strong acid




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[*] posted on 15-5-2018 at 23:37


That’s pretty much it, calcium oxalate precipitates out and HCl, being gaseous, can subsequently be removed from the reaction with heat (bonus, bubble it through DIW for relatively pure hydrochloric acid of your desired strength) further driving the equilibrium. Same as how sulphuric acid will liberate HCl from NaCl despite being quite the weaker acid, since the HCl won’t be hanging around to convert the bi/sulphate back.



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[*] posted on 16-5-2018 at 05:22


I actually did an experiment once where I left aluminum foil in magnesium chloride solution, oxalic acid solution, and a solution containing both. There was a white precipitate in the mixture, so I added the foil after allowing the solutions to all sit for an hour or so. The foil definitely dissolved most in the mixture.

However, it'd probably be better to filter or decant before attempting distillation, because oxalates tend to decompose easily, forming CO and CO2 (I think). And if those are acceptable impurities, you wouldn't even have to do that.

In that case, you have solubility driving the reaction rather than acid strength, and magnesium oxalate mostly removes itself from the reaction by being solid.

Edit: it works better for hydrochloric acid than sulfuric acid, because sulfuric acid can form bisulfate/bioxalate compounds that are relatively soluble. And sulfuric acid is a stronger acid. And oxalates tend to be reducing agents and sulfuric acid is prone to oxidizing things.

[Edited on 5/16/18 by Melgar]




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[*] posted on 16-5-2018 at 08:33


Eh, calcium oxalate doesn’t decompose (at least the monohydrate water) until at least 200 C, well above the temperature needed to distill off the HCl, which forms a ~20% azeotrope at 110C. Of course you should filter it first otherwise things are just messy at the least but there aren’t going to be any side reactions or unwanted byproducts unless the reagents are impure themselves.



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[*] posted on 16-5-2018 at 10:19


Quote: Originally posted by Formatik  
If you're after HCl, how about using no acidic compounds at all to form it? If you take some hydrated MgSO4 and NaCl, add some water to make a slurry and then heat on a hot plate first H2O comes off, then HCl and H2O, then just HCl. Any soluble inorganic Mg salt that doesn't decompose easily probably works in place of MgSO4. Make sure to do it outside and not in large amounts since HCl mist and gas are poisonous and
I find this method hard to believe. I get that you're going for the decomposition of MgCl2, but it seems like the overall neutral pH would muck things up, with all the water boiling away and the flask containing the starting materials.
However, it's also the only on-topic response which doesn't use the reaction of hydrogen and chlorine.
If you can obtain zinc sulfate, or zinc sulfide, which can IIRC be oxidized to zinc sulfate, this will undergo an easy salt metathesis with calcium chloride (DampRid, deicer) to zinc chloride, which then decomposes to release HCl gas. It might also be possible to make iron sulfate by oxidation of pyrite, although in this case SO2 will certainly be released. FeCl3 will undergo a similar decomposition to ZnCl2.
Alternatively you can make sulfuric acid from magnesium sulfate and oxalic acid (Bar Keeper's Friend, other cleaning products) which then facilitates making HCl.
I also think that sodium bisulfate + CaCl2 probably has some potential application here. The result of heating the mixed solution should be Na2SO4 + CaSO4 + HCl. IIRC NaHSO4 is common as a pH reducer for swimming pools etc.
And finally, the ammonium phosphate salts used in fire extinguishers will decompose to release ammonia gas leaving phosphoric acid at a high enough temperature. The stream of hot NH3 released is likely to be unpleasant.


[Edited on 16-5-2018 by clearly_not_atara]




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 16-5-2018 at 10:24


With respect to the Oxalic acid path, an old thread of mine where I and others experimented with H2C2O4, see http://www.sciencemadness.org/talk/viewthread.php?tid=18963#... .
-------------------------------------

Not sure if I mentioned the results of the reaction of NaOCl (chlorine bleach), NaCl and oxalic acid previously on SM, the advice is a warning, the reaction is exceptionally vigorous liberating Cl2 and CO2 per my experience!

Reactions:

H2C2O4 + 2 NaOCl --> Na2C2O4 (s) + 2 HOCl

2 NaCl + H2C2O4 --> Na2C2O4 (s) + 2 HCl

HCl + HOCl = Cl2 + H2O

Cl2 + H2C2O4 --Ferrous--> 2 HCl + 2 CO2

Reference on the action of chlorine with oxalic acid with a Fe(ll) or Mn(lll) impurity, see https://pubs.acs.org/doi/abs/10.1021/ja01208a024 and https://pubs.acs.org/doi/abs/10.1021/ja01198a052 , where a chain reaction mechanism has been proposed.

[Edited on 16-5-2018 by AJKOER]
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[*] posted on 16-5-2018 at 10:53


Going to the hardware store and asking for "Muriatic Acid" is by far the best method of all
That stuff is really dirty try reacting it with something and boil of the liquid you will be left with a bunch of gel like gunk left behind same with sulfuric acid they add some organic junk to it


forgot to add one more salt strontium nitrate and oxalic acid
To form insouble strontium oxalate and nitric acid
I mention strontium nitrate because it is more otc found in road flares along with sulfur powder than calcium nitrate

Simular concept as makeing sulfuric acid the quick and dirty way calcium nitrate a d sulfuric acid but instead with a weak acid

Nvm i look through the attached thread
Im amazed on how useful oxalic acid is

Pyrophoric metals from decomposition of oxalate
Iron
Nickel
Copper
Tin
Zinc
Lead


Nitric acid
Hydrochloric acid
Sulfuric acid although not sure but a test wth sugar and concentrating it in a ceramic container for those that dont have borrosilicate glass would be a great test the only problem is i think is driving to reaction forward

[Edited on 16-5-2018 by symboom]

[Edited on 16-5-2018 by symboom]




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[*] posted on 16-5-2018 at 12:27


If you feel like conducting an experiment just because the science is interesting, it's possible to produce HCl from NaCl by electrolysis. It's not the most practical preparation since it takes a lot of time and effort for a small amount of product.

This isn't the typical electrolytic procedure that produces gasses on both electrodes. In fact, you don't want any gasses to form on the electrodes in this case. The electrodes consist of very high surface area activated carbon, and the voltage used is less than 1 volt, not enough to cause charges to cross the double layers. Current is passed through the cell until the carbon is saturated and the current drops to near zero. This is essentially a demonstration of an aqueous supercapacitor and capacitive deionization.

Once the cell becomes fully charged, sodium has become adsorbed into the pores of one electrode, and chloride into the other. It's possible to recover the charge by disconnecting the voltage and applying a load across the electrodes. In this case the sodium and chloride ions reenter the electrolyte and mix together again. Alternately, one can remove the anode and cathode material (keeping them separate from one another), wash them thoroughly to remove any NaCl, and then obtain clean bulk activated carbon that contains either chloride or sodium.

If the same procedure is performed on something like oxalic acid, then hydrogen and oxalate-containing electrodes could be obtained. The hydrogen and chloride containing material can be mixed and stirred together to obtain HCl (might need a few days for this to complete), the pH being checked periodically. Adding a bit of NaCl to the mix would speed up the combination of the two elements by quite a bit. The HCl could then be purified by distillation in that case.


A more detailed and elegant write-up of capacitive deionization:

Attachment: Carbon electrode for desalination purpose in capacitive deionization.pdf (609kB)
This file has been downloaded 391 times




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