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Author: Subject: Production of Hydrochloric Acid
Aqua_Fortis_100%
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[*] posted on 19-10-2011 at 20:51


Unfortunately I have very little knowledge/experience on ceramics, though Im very interested in that field, specially in refractory materials.

Because of this great lack of simplicity in actually making the acid, Im another one that stick too with H2SO4/bissulfate method, but I dont forget the NaCl/SiO2/H2O route, just because it is kind like a "MacGayver survivalist route to HCl".. :P



BTW, pottery is not illegal in my country, but is hard to find a pottery store that does have on shelves good stuff, like oxides of barium, strontium, vanadium and all sort of exotic chemicals.

I found accidentally just one store of this kind on my city.. It was a very unique, happy, marvelous day..




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[*] posted on 14-7-2012 at 12:17


Making HCl in a satured ionically strenghtened solution, although doesn't fully warranty the yield, increases it, just as the case sulfur trioxide does not dissolve in water directly.



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[*] posted on 20-7-2012 at 11:40


Oxalic acid dihydrate (H2C2O4.2H2O) plus NaCl:

H2C2O4.2H2O + 2 NaCl --> NaC2O4 (s) + 2 HCl + 2 H2O

One can distill to capture and concentrate the Hydrochloric acid.

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

If one has access to inexpensive FeSO4, here is a pyrohydrolysis idea based on the reaction:

4 FeCl2 + 4 H2O + O2 → 8 HCl + 2 Fe2O3

Source: Wkipedia http://en.wikipedia.org/wiki/Hydrochloric_acid

So substituting a mixture of salt and FeSO4 for FeCl2 in the presence of H2O as:

2 NaCl + FeSO4 <---> Na2SO4 + FeCl2

one may be able to generate HCl via the pyrohydrolysis reaction:

8 NaCl + 4 FeSO4 + 4 H2O + O2 → 8 HCl + 2 Fe2O3 + 4 Na2SO4

which should be accomplished at a much lower temperature than heating salt and sand as has been suggested.

EDIT: Per the source "New Technologies for HCl Regeneration in Chloride Hydrometallury", pages 94-95, the process occurs in two steps given by the equations below:

12FeCl2(aq) + 3O2(g) → 2Fe2O3(s) + 8FeCl3(aq)

2FeCl3(aq) + 3H2O(g,aq) → Fe2O3(s) + 6HCl (g,aq)

so my new suggested procedure would be first the treatment of an aqueous solution of NaCl and FeSO4 with oxygen followed by, per the second equation, steam.

Per the cited paper, the first reaction stage is said to take place readily (2 hours) at 150 C . In the 2nd stage, the solution is heated to 175 to 180 C with the HCl stripped off at a conc of 30% with 99% yield.

Link: https://docs.google.com/viewer?a=v&q=cache:wptGS6Ben9IJ:...


[Edited on 21-7-2012 by AJKOER]
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[*] posted on 21-7-2012 at 06:06




One thing I've learned with these types of issues is that it is often nearly impossible to give an appropriate answer without knowing something about the asker's environment.

What is common and easily available here isn't necessarily common there.

A few examples....I'm in the US and 32% HCl is about $5/gallon about 2 blocks away at a pool store. I can't conceive of any way I could make it more cheaply, or even come close.

I once suggested that KMnO4 + NaBr + H2SO4 was the most straightforward and best way to make Br2. I was very surprised to hear chemists in Europe reply that H2O2 was the preferred way due to cost & availability. In the US, is is much more costly and difficult to get moderately concentrated H2O2 than KMnO4 (which is only about $10/lb on eBay). I could also buy it at most shops which cater to Koi fish pond owners.

Sodium? Cheap (almost) from GalliumSource. About $0.32/g @ the pound level in the US but much more costly to foreign buyers (who continue to buy there leading me to believe that many foreign amateur chemists don't have a comparable local resource).

So, while I feel I can sometimes offer constructive ideas on the chemistry involved, when it comes to what is the "best" way to get a reagent I try not to offer ideas unless I know something about the locale and its resources. It's easier than being wrong all the time....

A thought in passing....for some inexplicable reason, many users play coy about listing their true locations. If you actually give your country of origin you may receive answers more tailored to your circumstances.


[Edited on 21-7-2012 by Zan Divine]




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[*] posted on 21-7-2012 at 14:10


On a technical note, the reactions:

12FeCl2(aq) + 3O2(g) → 2Fe2O3(s) + 8FeCl3(aq)

2FeCl3(aq) + 3H2O(g,aq) → Fe2O3(s) + 6HCl (g,aq)

are described by the author (see 'Conclusion' on page 96) as the hydrolytic precipitation of iron as hematite accompanied by the volatilization of HCl under controlled temperatures, which is distinct from energy intensive pyrohydrolysis technology.

As such, my suggested process involving the replacement of aqueous FeCl2 with aqueous NaCl and FeSO4, is similarly best described as a hydrolytic precipitation/distillation process and not pyrohydrolysis.

Link: https://docs.google.com/viewer?a=v&q=cache:wptGS6Ben9IJ:...
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[*] posted on 22-7-2012 at 00:28


There is a thread in the acqcusition forum on the pyrolysis of PVC for making HCl(g).
...and, no, dioxines is not a problem if you do it right.




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[*] posted on 13-1-2015 at 15:01


Hi, I've got about 25kg of CaCl2 (it asserts that anhydrous) and 35kg of 85% H3PO4.
So I need to get HCl as gas (it will dissolve in distilled water) and Ca3(PO4)2- note that full substituted phosphate salt for further phosphrus production via coal and electric arc. But it will be later.
- Whether is it enough to warm the equimolar CaCl2+H3PO4 mixture? What should be the temperature to get the most substitutied yield?
- Do I need to concentrate H3PO4 more than 85% previously?
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[*] posted on 13-1-2015 at 15:17


Quote: Originally posted by Yo-Yo  
There is a thread in the acqcusition forum on the pyrolysis of PVC for making HCl(g).
...and, no, dioxines is not a problem if you do it right.

That was me.

Pyrolysing PVC yields literally Clouds of HCl gas.

The rate of HCl release is ridiculously high, driving all oxygen/air out of the reaction vessel almost immediately, when the vessel hits around 260 C.

'Doing it Right' is merely putting the PVC in a tin, and heating it over a wood fire.
The residue is basically an expanded matrix of carbon, so it would probably be OK in glass.

The difficult part is diffusing the HUGE HCl gas stream in water, and dissolving it before it escapes.




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[*] posted on 13-1-2015 at 20:31


Just about making HCl, some ... guy... at my school made it from his regurgitated fluids.
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[*] posted on 13-1-2015 at 20:52


New guy here... One thing I have not seen in the thread is the OP's required concentration.

I also will be using HCL in some cases, and looked around the "web" for formulas.
Some were brutal, and one stood out as a walk in the park. I'l post up the youtube link (hope that is appropriate), and hopefully it will help. All it requires is a bottle of Pool shock/Muriatic Acid ( 32% HCl), distilled water, and a few Tupperware containers.

I may be WAYYY off base but the reaction sounds credible, and the trouble saved seems worth the result. I suppose a titration would prove out the concentration.
Hope it helps.

https://www.youtube.com/watch?v=jv1Ms6Subg4




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[*] posted on 14-1-2015 at 15:11


Erm, Muriatic acid *is* Hydrochloric Acid no ?

Edit:

Ah. THAT video.

Yes, it works.

You end up with purer, but more dilute HCl solution.

[Edited on 14-1-2015 by aga]




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[*] posted on 14-1-2015 at 15:19


PVC pyrolysis yields smelly HCl.

It smells like burnt plastic, unsurprisingly.




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[*] posted on 15-1-2015 at 13:29


Quote: Originally posted by aga  
Erm, Muriatic acid *is* Hydrochloric Acid no ?

Edit:

Ah. THAT video.

Yes, it works.

You end up with purer, but more dilute HCl solution.

[Edited on 14-1-2015 by aga]


That is exactly why I think this method would be easiest.
I'm not sure but couldn't you evap. this product (Reagent grade HCL) to increase the concentration if needed? Or would the HCL evaporate as a whole, and just reduce the amount...

I'm learning, and trying to share what I learn.

[Edited on 15-1-2015 by Zombie]

[Edited on 15-1-2015 by Zombie]




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[*] posted on 15-1-2015 at 14:41


Robert Bruce Thompson's video shows how to Purify HCl.

Basically you get Purer HCl from that method with tupperware.

You get no New HCl.

The downside is that you get much less concentrated HCl.

Start with 30% and you get 50% max of the original concentration = 15%.

HCl dissolves up to about 36% by weight in water, so that's the maximum Hydrochloric Acid concentration you will get by any method : after the Limit, the water is saturated, and will simply not dissolve any more HCl gas.




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[*] posted on 15-1-2015 at 15:03


Quote: Originally posted by Zombie  

I'm not sure but couldn't you evap. this product (Reagent grade HCL) to increase the concentration if needed? Or would the HCL evaporate as a whole, and just reduce the amount...

Both. You can evaporate it to about 20% but some HCl will come off in the process. Once at 20% the HCl comes off at the same rate as the water, and thus the conc. will stay the same but the total quantity will decrease.




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[*] posted on 15-1-2015 at 15:59


Thank you for clarifying the purity, and concentration. Hopefully this will help Chemistry Alchemist as much as it helped me.

I'm loving this site!!!




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[*] posted on 16-1-2015 at 14:58


It is easily to prepare Hypochlorous acid, HOCl, as I have detailed previously (see opening thread at http://www.sciencemadness.org/talk/viewthread.php?tid=34429#... ) from aqueous NaClO plus CaCl2 followed by shaking in a large vessel filled with CO2. Reactions:

2 NaClO + CaCl2 = Ca(ClO)2 + 2 NaCl

Ca(ClO)2 + CO2 + H2O → CaCO3 (s) + 2 HOCl

Filter out the Calcium carbonate and one may opt to distill off just half of the starting HOCl as per Watts' Dictionary of Chemistry, Volume 2, page 16, the concentration of Hypochlorous Acid on a single distillation can be nearly doubled:

"A dilute solution of HCl0 may be distilled with partial decomposition, the distillate is richer in HCl0; Gay-Lussao found that, on distilling a dilute solution to one-half, the distillate contained five-sixths of the total HClO (C. R. 14, 927)"

I would then, let the HOCl stand in a glass vase sealed with plastic wrap in sunlight. Soon, you should see bubbles of oxygen and the smell of chlorine as:

HOCl + uv → HCl + O (g)
HCl + HOCl = Cl2 + H2O

With time (my experience was a week especially from uv reflecting off of snow), some Chloric acid, HClO3 (a very strong acid), will also be formed along with the HCl. The actual photolysis most likely proceeds along the following paths involving the species ·Cl, ·OH and ·ClO:

Cl2 + hv → 2 ·Cl
2 ·Cl + 2 HOCl → 2 ·OH + 2 Cl2 (g)
2 ·OH + 2 HOCl → 2 H2O + 2 ·ClO

forming, at most, one Cl2O2 as there are poisoning reaction paths, and finally:

Cl2O2 + HOCl → HClO3 + Cl2(g)

where at most one mole of Chloric acid for each eight moles of NaOCl given adequate sunlight, pH, ionic strength and solution concentrations.

As a reference, please see, for example, "Photolysis of free chlorine species (HOCl and OCl- ) with 254 nm ultraviolet light" page 281 and also Table 2, page 797 at http://www.geosci-model-dev-discuss.net/3/769/2010/gmdd-3-76... .

Note, adding a touch of a nitrate salt, will promote the photolysis reaction creating more HClO3 (via the hydroxyl radical pathway) if one so desires (reference, Hagg, W.R. and Hoigne, 1985).

[Edited] I should post a warning if the starting HOCl has dissolved CO2. In sunlight, it may be possible for CO2 to be decompose forming some CO and a species of oxygen (see page 1460 at https://www.google.com/url?sa=t&source=web&rct=j&... )

CO2 + hv → CO + 1/2 O2

The problem is the formation of CO, which could also react with Chlorine/uv to form COCl2, phosgene, a notorious poison gas. For safety, shaking the vessel to induce the reaction:

COCl2 + H2O → CO2 + 2 HCl

would be a safety precaution.

[Edited on 17-1-2015 by AJKOER]
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[*] posted on 16-1-2015 at 15:23


The sight of an AJ post really makes my day.

Happiness abounds.

[Edited on 16-1-2015 by aga]




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[*] posted on 18-1-2015 at 20:38


Gotta give him some credit, I've never seen someone consistently able to figure out the least feasible routes possible, and explain them in as much detail.

It's not meant as an insult @AJOEKR.
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[*] posted on 19-1-2015 at 15:56


Actually, this suggested preparation is based on actual (and unexpected) observed behavior of such a oxidizing solution I once created via photolysis (it bleached the hell out of part of the flooring in an old shower in my basement that I have been unable to replicate since with strong chlorine bleach). I did, however, prepare the Hypochlorous acid differently, via acetic acid on NaClO. The Sodium acetate was not removed as there was no distillation performed.

It should be noted that with sunlight, the reaction:

HOCl --uv--> HCl + O

has been reported to proceed more rapidly in the presence of Tartaric or Citric acid, which apparently act as catalysts (see "A comprehensive treatise on inorganic and theoretical chemistry", Volume 2, by Joseph William Mellor, top of page 82, where to quote: "According to C. Lowig,{27} bromine water in light behaves in a similar way to that of chlorine water, but as J. M. Eder showed, bromine water is much less sensitive to light in that it decomposes with but one-sixth or one-twelfth the speed of chlorine water. The presence of tartaric or citric acid accelerates the decomposition of chlorine or bromine water in light." Link: http://books.google.com/books?pg=PA82&lpg=PA82&id=An... ).

My recent readings also note in general that organic compounds in water generally (and acetic acid, I would guess in particular) appear to promote the formation of hydroxyl radicals (and there in, HClO3 in addition per the action of radicals discussed above). See, for example, "Chemistry of Marine Water and Sediments", edited by Antonio Gianguzza, Ezio Pelizzetti, Silvio Sammartano,.. , page 90, at https://books.google.com/books?id=DacPIDoNaNQC&pg=PA90&a... detailing the formation of H2O2, which can produce hydroxyl radical under photolysis.

Now, I also even recall one paper discussing the formation of even perchlorates via photolysis. See, for example, "Perchlorate production by photodecomposition of aqueous chlorine solutions", abstract at http://www.ncbi.nlm.nih.gov/pubmed/22962844 .

So bottom line in my opinion, there appears to be some observations and theory suggesting that one may be able indeed to create quite a strong acid via HOCl, an organic catalyst (I would revise my suggested preparation above with the addition of a mix of critic or acetic acid on NaClO), good uv exposure (using the presence of snow , for example) and a good amount of time.

[Edited on 20-1-2015 by AJKOER]
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[*] posted on 19-1-2015 at 22:54


While it's much cheaper for me to buy HCl at the hardware store, the easiest way to make that I've found is mixing sodium chloride and magnesium sulfate hydrate.
2NaCl + MgSO4•6H2O <--> Na2SO4 + MgCl2+ 6 H2O
MgCl2•2H2O + heat --> Mg(OH)2 + 2 HCl(g).
Magnesium sulfate hexahydrate is less than $3 a pound at the pharmacy and even that's a ripoff.

[EDIT]
Magnesium sulfate hexahydrate has a MM of about 192, and each mole will make two moles of HCl, add it all up and 3 dollars worth of Magnesium sulfate hexahydrate will get you 457 grams of 37% HCl assuming 100% yields and not including NaCl's price.


[Edited on 20-1-2015 by Zyklon-A]




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[*] posted on 26-1-2015 at 11:35


And what is the process used here?



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[*] posted on 25-5-2015 at 21:17


http://www.sciencedirect.com/science/article/pii/S0165237011... - The thermal decomposition of magnesium chloride dihydrate.
doi:10.1016/j.jaap.2011.02.005
You need 200°C to get half of the HCl, and the rest will be given off only after reaching 413°C.
MgCl2*6H2O -- 150°C --> MgCl2*2H2O -- 200°C --> MgOHCl +HCl -- 415°C --> MgO +HCl
You can concentrate a dillute HCl via CaCl2 dehydration http://www.qvf.com/qvf-process-systems/mineral-acids/concent...
Dronami_inc told want to react CaCl2 and H3PO4, and I think it's a great idea, because CaHPO4 and Ca3(PO4)2 have extremely low solubility, while NaCl+H3PO4 give almost no reaction even after heating (and you can't heat it too high in a glass or porcelain apparatus).
NaCl + H3PO4 --> ???
In my experiment, after mixing NaCl and H3PO4 I was able to detect a slight smell of HCl at r.t. and after heating to 50°C HCl started to come off slowly. However, it took like 10 seconds to obtain a clearly visible coloration of a litmus paper above the mixture surface by HCl.
CaCl2 + H3PO4 --> HCl + Ca3(PO4)2
Mixing anhydrous CaCl2 and H3PO4 led to a problem of insoluble calcium phosphates on the surface of CaCl2 particles. That's why strong agitation is required forthis reaction to proceed. It heats itself, and the HCl is given off pretty intensively, changing coloration of litmus papper in a second.
It looks like a good idea to use a concentrated water solution of CaCl2 (140g/100ml at 90°C) for the reaction, because this way you can avoidthe need of agitation: the whole stuff becomes mostly homogenous, with a fine powder of calcium phosphate of the bottom and relatively pure HCl solution in water.
I've tried something like this: 14 g of CaCl2 hydrate + 10 ml of water + 14 g of H3PO4. As you may calculate, the resulting mixture contains 4.6 g of HCl in 12 ml of water, which is 28% concentration. As I can see, it gives off a heavy smoke of HCl first, then a more dillute HCl+H2O comes off should come off.
As I've already told, you can use a dehydration agent to concentrate the dillute acid, like anhydrous CaCl2 made by heating a hydrate to 235°C or CaCl2*H2O by heating the hydrate to 175°C, and the best you can obtain from MgCl2*6H2O is dihydrate by heating to 130°C (not higher then 160°C, because it starts to give off HCl at 160-170°C).
The funny and sad thing is that H3PO4 is actually made by reaction of H2SO4 and Ca3(PO4)2 or from white phosphorus, that's why the whole method of ours HCl production would not make sense without a cheap industrial source of H3PO4. And MgCl2 is made by action of HCl on Mg(OH)2 or magnesium carbonate (magnesium doesn't like to fully substitute the acids, so it's often exists as a MgCO3·Mg(OH)2·nH2O compound).
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