Argox (Newbee)
12-03-01 12:51
No 243555
      Best Method for Hydrochloric Acid Gas  Bookmark   

Best Method for Hydrochloric Acid Gas

The experienced chemists on this forum will probably scoff at the notion that anything so simple as hydrochloric acid gas (hydrogen chloride or HCl(g)) would require careful explanation as to proper methods, set-up and precautions.  The grim reality is that novice chemists have killed themselves as a result of ignorance regarding HCl(g). 
A cursory review of Rhodium’s page and the Hive search engine (TFSE) regarding methods to produce HCl(g) and store it for future use reveal incomplete information, poorly written information, and a certain degree of debate among Hive members as to the best method.  Rhodium’s Post No 218531  provides outstanding examples of ghetto devices for the manufacture of HCl(g), most of them dangerous, none reusable, and all obvious evidence of illicit activity.
HCl(g) is not illegal to own or make.  It is sold commercially as a compressed
 gas at 2000psi in CS cylinders.   The commercial cylinder requires a CGA 330 fitting and single stage SS regulator ($us350).   The regulator must be purged with nitrogen after every use; even so it has a limited life span and will require refit or replacement on a regular basis. 
Commercial cylinders of HCl are regulated.  The supplier is required to fill out certain forms and send the data to certain government agencies with every purchase.
Most chemists, legitimate and clandestine, prepare HCl(g) in the laboratory, to avoid the cost, hassle, and danger of compressed gas.  A review was conducted of four OTC methods, and the best method was determined. 

Four common OTC methods were examined:

1.  Muriatic acid dripped over sulfuric acid
(drain cleaner).
2.  Sulfuric acid (drain cleaner) dripped over table salt.
3.  Table salt mixed with sodium bisulphate and heated.
4.  Muriatic acid boiled.

All four methods produce HCl(g) in varying yields.  However, one method was clearly superior to the others based on yield, speed of reaction, and, most importantly, in situ clean-up and reload of reactor.  The best method to produce HCl(g) according to these criteria is reaction 1. --dripping muriatic acid over sulfuric acid.   For the benefit of the novice, a detailed discussion of this method follows. 
In addition, two commonly used solvents were examined (acetone and IPA) to determine which was the best for collecting and storing HCl(g), since there are empirical benefits to be obtained by collecting and storing HCl(g) for future use in order to precisely dose certain bases, rather than the more uncertain, unwieldy and dangerous practice of direct gassing those bases.   It was determined that IPA is superior to acetone.

Best Method.
Dripping muriatic acid over sulphuric acid. 

HCl(aq) + H2SO4 => HCl(g) + H2SO4(aq)
This method is superior to others for the following reasons:
1.  Yield of HCl(g) is above 90% of theoretical, based on manufacturer’s label of HCl content in muriatic acid. 
2.  The speed at which gas is generated can be more precisely controlled than with the other methods, thereby increasing safety.
3.  Excessive heat or dangerous conditions are avoided.
4.  The reactor can be cleaned and reloaded in situ (without taking the gas apparatus apart) in a few minutes.  This aspect is important when larger quantities of gas are required.  In fact, the ability to quickly and easily unload and reload the reactor in situ probably should be the only critierion for determining the best method.  The fact that equipment can be easily cleaned and reagents discarded in an environmentally safe manner should be of value to the clandestine chemist, since there would be no left-over evidence of illicit activity by using this method.

Obtaining ingredients.
To produce HCl(g) with this method in North America one should buy muriatic acid and drain cleaner from the (big orange) hardware store and 99% isopropanol (IPA) from any drug store.  The novice should make sure the label of the muriatic acid says "contains hydrochloric acid" and "muriatic acid commercial 31%," make sure the label of the drain cleaner says "contains sulfuric acid," and make sure the label on the IPA says 99% and "isopropyl alcohol."

Testing ingredients.  
There is no need to test the muriatic acid, other than mak
ing sure that the label does indeed say muriatic acid.  Confirmation that it is muriatic acid comes when the top is taken off the bottle and the characteristic fog of acid vapor rises out of the bottle.  Do not breath this vapor: it is pure hydrochloric acid produced by the reaction of HCl(g) with water vapor in the air. 
Test the drain cleaner/sulfuric acid by weighing 500 cc.  Drain cleaner/sulfuric acid is a heavy dark liquid and 500 cc should weigh between 917 and 920 grams.  If 500 cc weighs substantially less than 917g, then it has been diluted with water and cannot be used.  Look for a different brand of drain cleaner or obtain commercial-grade sulfuric acid, a non-watched chemical.  The specific gravity of sulfuric acid is 1.84.  1000cc weighs 1840g.  500cc weighs 920g.
Test 99% IPA by dripping one drop onto a clean mirror and holding the mirror up against a light bulb.  If the
'IPA is truly 99%, then the drop will evaporate without leaving any smaller drops on the mirror.  The presence of a number of miniscule cloudy drops on the mirror after the initial drop has evaporated indicates water contamination.  If this be the case, buy another brand of IPA or dehydrate the IPA with 3A molecular sieve, anhydrous MgSO4 or similar anhydrous salt.  The various methods of removing moisture from alcohols and other solvents have been thoroughly discussed in numerous posts.

Setting up equipment
This discussion of equipment is predicated on two personal philosophies:

1.  Neither wise men nor fools can work without tools.
2.  No amount of money saved on substandard equipment is worth the cost of it failing.
The novice may find this discussion of laboratory glassware daunting.
However, the benefits obtained from using proper glassware outweigh the costs, as per the above two points. 
(Note--the Rhodium chemistry page contains a write-up by Psychokitty describing a gas generator using beer bottles and syringes.  That write-up is a "ghetto" alternative for the novice CC who needs only grams of HCl(g) rather than kilos and who cannot afford good equipment.)
The gas generator consists of four main pieces: 1) the equalizing addition funnel with teflon needle valve; 2) the reactor (an RB flask, ehrlenmeyer flask, or kettle; 3) the bubbler (an RB flask or ehrlenmeyer flask); 4) the receiver (an RB flask or ehrlenmeyer flask).  These are connected by a claisen adapter, two 3-way vacuum adapters (suggested is a custom vacuum adapter that includes a stopcock for pressure relief), and joint-to-hose adapters.  A stopcock or way of relieving line pressure should be placed betwee
n the reactor and the bubbler, and the bubbler and the receiver.  All glassware should use standard taper joints, 24/40 is fine (it is suggested that rubber stoppers not be substituted for standard taper joints--rubber stoppers will degrade in the presence of HCl and eventually leak).  Lab-grade silicone grease must be used on all glass joints (vaseline should not be substituted for lab-grade silicone grease).  Also suggested is that each glass joint be secured with a Keck clip (24/40 Keck clips are green) or SS wire clip.
All of the above glassware should probably be part of any novice chemist’s equipment inventory.  In addition, to properly perform this method for producing HCl(g), the chemist should also purchase 2 magnetic stirrer hotplate combos and several magnetic stirbars (egg-shaped stirbars must be used for RB flasks).  These stirrer/hotplates will be useful for many other reactions and will form an essential part of  the equipment for other syntheses.  None of this glassware or equipment is watched or controlled or illegal to own, as long as any RB flask is not 10L, 12L, 20L or 22L in size.  A 2L equalizing addition funnel, a 5L FB or RB flask for the reactor, a 500 ml RB flask for the bubbler, and a 1L RB or ehrlenmeyer flask for the receiver are sufficient to produce substantial--even industrial--quantities of HCl(g) in a day, plus this glassware can be used for many other interesting reactions.  A drawing of a gas generator can be found at the end of this post.

Muriatic acid, a mixture of water and HCl, is slowly dripped into a stirred flask containing sulfuric acid.  Sulfuric acid has a strong affinity for water.  The sulfuric acid dehydrates the muriatic acid, absorbing water and liberating HCl(g).  The liberated HCl is then bubbled through a smaller quantity of sulfuric acid to remove any trace of water vapor, and then the dry gas is absorbed in stirred, cold IPA.   By weighing the IPA before and after gas absorption, the exact production of HCl can be determined.  This exact amount of HCl is very useful in subsequent reactions, since stoichiometric amounts of HCl can be dosed into base/solvent mixtures, in contrast to direct gassing of such mixtures, which is a "hit or miss" and exothermic operation.  The HCl/IPA mix is stable and can be stored for future use, unlike HCl/acetone mix, which quickly degrades.  IPA is not hygroscopic as is acetone, another important consideration.  (Bees may note that this information is in contrast to several major Hive write-ups where HCl loading into acetone and/or direct gassing is recommended.)

Practical application.  
Use 2 parts by volume of sulfuric acid/drai
n cleaner for every 1 part of muriatic acid.  Put another way: use 2 bottles of drain cleaner for every 1 bottle of muriatic acid.  (This will provide an excess of sulfuric acid necessary for proper dehydration of the muriatic.)  The most important consideration is to constantly stir the sulfuric acid/drain cleaner while muriatic acid is being dripped.  If the sulfuric acid is not stirred, a layer of muriatic acid will form on top of the sulfuric acid and when the flask is moved for any reason the two layers will mix with violent release of HCl(g).  THEREFORE always stir the sulfuric acid while adding muriatic acid, this stirring cannot be avoided without disasterous results--so the magnetic stirrer is essential.  Repeating again, ALWAYS stir the sulfuric acid while adding muriatic--do not shake by hand--stir with a magnetic stirrer and telflon coated stirbar.  The gas bubbler is another important part of the set-up because it allows visual evidence of how much gas is being
 produced and it removes any water vapor that might come over with the HCl(g).  The goal is to produce anhydrous HCl(g), since water vapor is detrimental to most hydrochloride crystallizations for which one would use HCl/IPA.  Since HCl(g) is completely absorbed by cold IPA to a loading of 25% or greater, there will be no bubbles coming out of the receiver flask after the initial air is driven out of the gas generator set-up, therefore the bubbler provides the only visual indication as to whether the gas generator is going full blast or has stopped or has sprung a leak (although in the case of a leak, the characteristic mist of HCl(g) and the smell will be evident).

Suck-back occurs when the amount of gas being generated cannot overcome the rate of absorption.  A trap must be placed between the gas generator and the receiver as a safety precaution to collect any IPA sucked-back.  To control suck-back, a stopcock placed before the bubbler and before the receiver will
 allow the operator to relieve line pressure.

Additional tips.
Do not use a dispersion tube while absorbing HCl(g) into IPA, as has been recommended in other posts.  The dispersion tube is not needed since HCl(g) is immediately soluble in cold IPA.  The dispersion tube could increase line pressure and cause a joint or flask to pop.   3/8" ID polyethylene tubing such as can be purchased at the (big orange) hardware store is sufficient for both the bubbler and the receiver.   Stainless steel tubing is not recommend--this is in contrast to what has been suggested in another major Hive write-up--since HCl will corrode stainless steel and chromium/nickel/iron chlorides  will go into solution and possibly contaminate the final product.  Telfon hose is recommended for glass joint to hose connections; however, the clear vinyl hose found at the (big orange) hardware store can be used once.  All hose connections must be fastened with hose clamps (obtained from any hardware store). 
With proper fittings this apparatus will not leak and will not smell, but working under a fume hood is always a good general practice.
Yield is close to theoretical.  Over 300g of HCl(g) will be produced from a 900ml bottle of muriatic acid in about 2 hours of slow dripping.  Once the gas production begins to diminish, the sulfuric acid in the reactor can be heated and additional HCl(g) recovered (this is where the stirrer-hotplate combo comes in handy).  If more than 10kg of HCl is needed in one day, then acid addition will have to be much more rapid, requiring larger size flasks and larger bore tubing to accomodate the increased reaction rate, but the novice should not need more than a few kilos of gas in one day, which can be generated with a 5L reactor.

Clean-up and reloading. 
The most important advantage of this method is the fact that without taking the apparatus apart, the
} spent sulfuric acid can be pumped or siphoned (by vacuum) out of the reactor and then poured into a plastic pail of cold water and flushed down the toilet (after all, the label did say "drain cleaner").  Local water treatment plants can handle sulfuric acid no problem and those drains sure get a good cleaning.  Reload is as simple as pouring or pumping another couple of bottles of drain cleaner into the reactor.  None of the other common methods are as simple to unload and reload, their yields do not come close to theoretical, they are not appropriate for larger scale production.  A discussion of the other methods follows:

Other methods:
Reacting sulfuric acid and table salt.  Note that contrary to many posts and even government web pages this reaction produces sodium bi-sulfate, not sodium sulfate.  Therefore the sulfuric acid:salt mole/mole ratio is 1:1, not 1:2.  The reaction mechanism is:

H2SO4 + NaCl =>  HCl(g) + NaHSO4

(The reaction of sodium bi-sulfate and table salt to produce hydrogen chloride only takes place at elevated temperature (+250ºC).) 
Hive Bees fervently defend this method of dripping sulfuric acid over table salt, yet it is inferior to the recommended method for these reasons:
1.  The salt/sodium bi-sulfate cake in the bottom of the reactor cannot be stirred using a magnetic stirrer, and it can be seen that even with overhead stirring (using a seal) the cake cannot be easily stirred, and without stirring the reaction is slow and yield is much less than theoretical.
2.  The production of HCl(g) cannot be controlled by control
ling addition of sulfuric acid, since sulfuric acid builds up around the salt cake and reacts independently of the dripping.
3.  The salt/sodium bi-sulfate cake cannot be removed from the reactor without taking the apparatus apart, which fills the area with HCl vapor as a result.  Therefore, rapid unload and reload is not possible, limiting the amount of hydrogen chloride that can be produced in a day.
4.  The salt/sodium bi-sulfate cake does not easily come out of the reactor, but requires washing with hot water and shaking to dislodge.  Producing 3 to 10 kilograms of HCl(g) using this method and a 5L reactor would take substantial effort and time and would release an undesirable amount of HCL vapor into the work area, compared to the recommended method.   Overall this method is inferior.

A third method is heating table salt and sodium bisulphate.  The reaction mechanism is:
NaCl(s) + NaHSO4(s) + delta temp. => HCl(g) + Na2SO4(s)
This method is also inferior for the following reasons:
The temperature in the reactor must reach +250ºC for the reaction to commence.
2.  Although stirring is not required, because the two powders are mixed before charging the reactor, the yield is much less than theoretical because the two compounds can never come into intimate contact.
3.  A very hard cake of salt/sodium sulphate remains in the reactor after cooling.  This cake can only be removed with copious amounts of hot water and much shaking and cursing.  Time is wasted while heating the mix, time is wasted while waiting for it to cool down, time is wasted removing the cake from the reactor.  Impossible for larger scale production. 

A fourth method is boiling muriatic acid.  The idea is to reduce the solubility product of HCl in water by boiling muriatic acid.  However, hydrogen chloride forms a constant boiling mixture with water, such that a great deal of water vapor comes over with the HCl and quickly dilutes the sulfuric acid bubbler.  Yield is unacceptable compared to any of the above reactions.  Although the reactor can be pumped or siphoned out and reloaded, the remaining liquid still contains substantial amounts of HCl which even cooled and poured into water releases HCl vapor into the work area, very unpleasant to handle, and not something to pour down the drain since it is highly corrosive.  An inferior method and not recommended at all.


Of the four common methods to produce HCl(g) using OTC ingredients, one method was shown to be superior in terms of yield, reaction time, controllability, and ease of unload and reload, which is the most important aspect for larger-scale production.  The superior method is dripping muriatic acid into sulphuric acid, preferably with the gas generator equipment described.
It was also determined that IPA is superior to acetone as a solvent in which to store HCl for future use, since it will not degrade over time, is non-hygroscopic, and is compatible with common processes that require hydrogen chloride to precipitate hydrochloride salts from solvent/base mixes.  It is a personal opinion that HCl(g) should be dissolved into cold IPA regardless of whether gas is generated as described above or obtained from a compressed gas cylinder, before dosing a solvent/base mix for two reasons:
1) to insure that only a stoichiometric amount of HCl is added; and 2) to avoid the heat of dissolution which may degrade the product.

I hope this post will be of value to the novice chemist.


(The equipment drawing (which I spent hours on) won’t come up on the computer I am using to send this, so will have to be posted at a later date—that is, if anybody cares.)
(Chief Bee)
12-03-01 12:59
No 243558
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Send the drawing to and I'll put the complete document on my page. Great work!
12-03-01 13:11
No 243565
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Rhodium--you are amazing!  I just posted this less than two minutes ago and already you have read it and replied.  Do you ever sleep?  Thanks for encouragement.
(Chief Bee)
12-03-01 13:34
No 243574
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Yes, I do sleep sometimes, but not during the american night, I'm ~8 hours before you US bees.
(Old P2P Cook)
12-03-01 18:55
No 243657
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

It was also determined that IPA is superior to acetone as a solvent in which to store HCl for future use, since it will not degrade over time
Couple of nits:

1) Are we sure that IPA/HCl does not degrade over time? Seems like if I stored the stuff at room temp. for a while that I would start getting isopropyl chloride or propene.

2) What is the solubility of HCl in 99% IPA?
(Stoni's sexual toy)
12-04-01 00:24
No 243777
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

> Are we sure that IPA/HCl does not degrade over time?
> Seems like if I stored the stuff at room temp. for a
> while that I would start getting isopropyl chloride or
> propene.

I've seen 1M HCl in IPA available from a chemical supplier, so it must be somewhat stable, otherwise they couldn't sell it.

> What is the solubility of HCl in 99% IPA?

According to Argox:
"Since HCl(g) is completely absorbed by cold IPA to a loading of 25% or greater..."
Sounds a bit high to me, but if he says so then it might be true.
I'm pretty sure that IPA will hold enough HCl to convert more MDMA freebase into the hydrochloride than it is able to hold in solution.
Attention: don't store bottles of solvents saturated with gasses! And if you have to, do NOT fill them more than 30 or 50% of capacity! Also make sure the storing conditions match those encountered during manufacture. It's a bitch when your fridge breaks down and the bottle explodes inside due to overpressure!
12-04-01 04:07
No 243896
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

MadMax is right: 613 psi on hydrogen chloride gas cylinder is correct.  I wrote that part from memory trying to recall what the gauge marked on fresh cylinder--memory must be failing me in old age (too many cylinders, so little time).  I know the rest to be accurate.

To get almost all MDMA.HCl from IPA/acetone solution, reduce temp to -15C, additional crystals will form after several hours.  Then recover the remaining MDMA by boiling off solvents atmospheric pressure. (solvents recovered over CaCO3 anydrous to remove acidity and 3A mol sieve to remove water).  The usually substantial amount of MDMA remaining due to fact that water is inevitable in acetone/IPA/HCl solution can be basified (use DCM wash of water) and redistilled with next batch.  This is what SWIA does, but hey, you guys are the Hive mavens, he's just a newbee. 
12-05-01 17:47
No 244495
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Nice post argox - well written.
Regarding the stirring  (IMPORTANT-noted!)with the HCL addition.If swim didn't have a magnetic stirrer could you agitate the solution with a fish air bubbler ? The air would be dry as it goes through the H2SO4 but could be dried before passing through anyway. What is the consequence of excess dry air passing through with the HCL gas into IPA or whatever you are piping your HCl gas into?
If this is not a problem then it is immediately obvious that the system is operational when the aeriator is turned on and could this also prevent suck back problems?

Thanks and keep it up

"Now they call taking drugs an epidemic - that's 'cos white folks are doing it - Richard Pryor.
12-07-01 14:16
No 245286
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Any chance of an answer or is it that stupid a question?

"Now they call taking drugs an epidemic - that's 'cos white folks are doing it - Richard Pryor.
(PVC-Analog Taste-Tester)
12-07-01 17:00
No 245314
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

"If swim didn't have a magnetic stirrer could you agitate the solution with a fish air bubbler ?"

  An air bubbler would make things more complicated than they have to be; pressure, etc.. I've made my own magnetic stirrer: Put one stirring magnet into the flask, superglue another onto a small electric motor. Suspend the flask about 1/2 inch away from the motor. I've been stirring solutions this way for about 2 years now. Maybe I should stop being such a cheap bastard and buy a real stirrer. Peace!laugh

  Split a piece of wood and I am there. Lift a stone and you will find me.
12-07-01 23:01
No 245395
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Mr. R.

Sorry not to respond quickly--I only log onto Hive once or twice a week usually.

I really couldn't recommend that you use an air bubbler.  In fact, I'd say don't do it.  SWIA had a bad experience when the sulfuric acid was not well mixed and a layer of hydrochloric formed on top of it.  (Remember that sulfuric is almost twice as dense as hydrochloric.)  When the flask was shaken a little, the reaction was uncontrollable and blew the addition funnel (the only thing not clamped down) straight up, not to mention the acid gas frying all metal parts under the fume hood (a really nice overhead mixer, which SWIA should have been using, had all its copper contacts instantly corrode).  SWIA was wearing eye protection, thank God!, and escaped with only swiss cheese for a lab coat.  Like, live and learn.  Hence strong emphasis on safety in the write-up.

A hotplate/stirrer combo only costs a couple of hundred bucks, you'll use it over and over again, and like I said in the post, the money saved on sub-standard equipment is not worth the cost of it failing.

Good luck.

Rhodium and I are still trying to connect on the drawings, but they should be posted soon, so you'll see what I was talking about.


(Hive Bee)
12-19-01 02:38
No 248808
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

IMHO the table salt/sodium bisulfate method is the best for newbees as it doesn't require any drying or anything (as both the salt and the sodium bisulfate come as pretty much dry solids).  All the other techniques require u to try to dry some form of liquid acid, which can be a bit of a pain in the ol' ass.

You are unique....just like everyone else.......
(Junior Service Representative)
12-19-01 02:46
No 248814
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Where does the H+ come from when using the two solids?


(Chief Bee)
12-19-01 02:50
No 248818
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

NaCl(s) + NaHSO4(s) => Na2SO4(s) + HCl(g)

Can we have a practical writeup of this on a molar scale, and I'll add it to my page.
(Junior Service Representative)
12-19-01 02:55
No 248820
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Ahhh, bisulfate does not equal (SO4)2, which would be disulfate...


12-19-01 22:13
No 249011
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

There is a very imformative site on generation of such gas ussing such method try a www search on microscale gass or microwave gass the site does not alow direct links

one uses the monohydrate or the dehydrate preferably, I am not shure if the monohydrate can be dehydrated? a specific protocall might be nice......

Basicially ya lube up a big syringe w/ silicone spray lube and place a little hcl in there atop the sodium sulfate and nuke for about 15 seconds then the gas is in the syringe basicially

theres a whole bunch of other gasses featured in the general layout of the site such as h2S etc

I know sometimes when drying a salt you get a tranformation into something alltogether different often times this changes the PKA pH etc like baking soda to washing soda

(Hive Bee)
12-24-01 23:55
No 250305
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Sorry to drag threads up after they have been laid to rest, but I don't check Hive too often, and this was my post, Sooo:
Replying to:
IMHO the table salt/sodium bisulfate method is the best for newbees as it doesn't require any drying or anything (as both the salt and the sodium bisulfate come as pretty much dry solids).  All the other techniques require u to try to dry some form of liquid acid, which can be a bit of a pain in the ol' ass.

I disagree.  I have tried each of the mentioned methods, not once, not twice, but many times, trying to perfect each one.  The recommended method from my post is the BEST method, for Newbees, for experienced lab techs, for anybody.

The only acid that needs to be dried is acid GAS--not "liquid acid."  Hydrochloric acid gas is easily dried by bubbling through sulphuric.  It has to be done no matter which method is used, and is not a "pain in the ass", but rather a necessary step to insure a high return of crystalline hydrochloride product.

I want all newbees (like me) to disregard using sodium bisulphate and salt as a source for HCl.  Use drain cleaner and muriatic as per post.  Reasons?  A couple of things...

Who said sodium bisulphate is "dry?"  It is not completely anhydrous, but carries waters of crystallization, and it WILL pick up water from the atmosphere.   (Yes, I know the label on the sack of NaHSO4 says "anhydrous", but take it from me, it carries some water, more than we want.  "Anhydrous" is this case is meant to differentiate it from the sodium bisulphate hydrate salt, which carries a couple (I don't recall exactly how many) of water molecules--but does not mean completely water-free.)  Table salt is certainly not "dry", but also carries water in its crystalline structure.  I know for a fact that when the two are heated, water vapor is formed and will follow over into the solvent collecting the HCl, if the gas stream is not dried.  But the main drawback with sodium bisulphate is not the water--it is the fucking heat!

The reaction takes place at elevated temperature.  Like red hot.  +350C to 500C.  Any fuckup with suckback of IPA or acetone into the reactor and somebody is going to have shards of glassware flying around the lab.

Once the reaction takes place (as in the reactor reaches 500C) a LOT of gas is produced all at once.  Unless the reactor is a pressure vessel with a valve to control the gas stream, the bulk of the gas will come out in a short period of time--it's not a steady release, but is shaped like a bell curve.  Jeez, when I think of all the problems I had with bisulphate, I could go on and on.  I even tried to make a SS pressure vessel with external heating--I mean, I really tried everything.  Just stick with the recommended method.  So easy.  By this time Rhodium should have the drawings of the recommended set-up, and perhaps can post them somewhere.

Sure, for a lab demonstration to impress kids, you can mix salt and NaHSO4 in a test tube, heat, and collect HCl in a syringe.  But for day-in and day-out steady production of HCl when no cylinder is available, forget it.  The same with salt and sulphuric acid.  Forget it.  The recommended method is the BEST method.

(Hive Bee)
01-04-02 04:14
No 252382
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Yes mrReflux, the dry air wouldn't be a problem cause it's not wet! And the suck back problem would be reduced if not taken right away.

Hey , cheese seem to remember quite a few bees creating hydrogen gas quite easily by dripping HCl on balls of aluminum foil, the side product is hydrochloric gas. This isn't the best method but seems to be sufficient for small amounts of product being produced. The HCl/Ag react so hot that it boils the HCl and thus creates it's gas. Guess it was mentioned that boiling HCl is one way, only Ag wasn't mentioned. Oh well, it's meant for ghettoboys anyways.

May The Source Bee With You....Always.
(Hive Bee)
01-04-02 05:24
No 252422
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Replying to:
Hey , cheese seem to remember quite a few bees creating hydrogen gas quite easily by dripping HCl on balls of aluminum foil, the side product is hydrochloric gas. This isn't the best method but seems to be sufficient for small amounts of product being produced. The HCl/Ag react so hot that it boils the HCl and thus creates it's gas. Guess it was mentioned that boiling HCl is one way, only Ag wasn't mentioned. Oh well, it's meant for ghettoboys anyways.

Ag is silver, Al aluminum.  Hydrogen is one thing,  hydrogen chloride is another.  But truth be told, my only comment is--whatever.

(Hive Addict)
01-08-02 22:21
No 254118
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Whatever happened to the pic of HCL genorator???


"The gods are too fond of a joke."  (Aristotle)

(Chief Bee)
01-08-02 23:10
No 254134
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

I have it. It will be placed on my page shortly in the document.
(Hive Addict)
01-12-02 03:15
No 255492
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

I appreciatetheinformation on saturated IPA.

However, I will contend as I have before
much to the bemusement of some,
that bubbling air thru HCL,
and thence thru a drier,
and then to the reaction vessell,
is in fact the easiest, most foolproof,
and expeditious method for many.

1.  on/off readily.
2.  little or no chemical hazard.
3.  relatively inexhaustible.
4.  cheap

1.  slow, compared to the more concentrated gas
achieved by some above methods.

this can be ameliorated by:
a:  Warming the container.
     1.  THIS can be done easily
by placing in a crock-pot cooker..

     2.  Because the system takes ZERO attention,
the 10 minutes to 1/2 hour it takes(for the process)
is not excessive. (IMHO)


A $6 aquarium pump,
two 2 hole stoppers, 
and some tubing...

I am appreciative of the work it took
to make the comparison,
and the presentation style
is one I should emulate.

I would invite you actually trying this
and commenting,
because most who take a dump on it
have not tried it:

whereas I have tried two of the above
and consider this technique superior.

Until you experience

"stick in the tube
and flip the switch"
you'll not appreciate it..

PS:the drier which I currently use,
epsoms in a Snapple bottle,
is overlain by some
indicating material which
advises when water vapor is
getting to it.

The epsoms is
rapidly and thoroughly dried
in the microwave.

Thank you.


(Distinctive Doe)
01-12-02 05:37
No 255527
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

" 10 minutes to 1/2 hour it takes(for the process) "

Holy shit
I would bee asleep by then.  Or I would bee off on some other project and forget about the gassing until like 4 hours later.

Thats just way to damn SLOW!!!

I hate my government, does this mean I'm a terrorist??
(Hive Addict)
01-12-02 09:54
No 255566
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

it's also extremely inefficient, considering you waste a lot of drying agent and muriatic acid for the amount of gas produced.  There's nothing that complicated about gassing with sulfuric and salt; why bother with anything else? 

If Pacman had influenced us, we'd run around dark rooms eating pills and listen to repetitive music
(Hive Addict)
01-16-02 02:04
No 256907
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Slow I copped to: Generally 10 minutes is not thatprecious to me..

As for my friend GJ?
Yeah, that epsons is damned expensive.

And the waste of muriatic?  No question: for the HCl you produce, you leave behind all that water,.  Or istheir something else in muriatic besides hydrogen chloride and water?

??  the world waits for revelation..?? laugh

(Chief Bee)
01-16-02 06:51
No 257027
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

This document now available at ../rhodium/chemistry /hclgas.argox.html with apparatus diagram.
(Junior Service Representative)
01-16-02 17:18
No 257228
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Yet another sweet document,


01-20-02 23:09
No 258747
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

seems swim must break his mute silence, his vote is for dwarfers rig, as modified by the muses, i.e. - rock salt, muriatic, an occasional drop or two of sulfuric and an occasional bit of foil, penetrated via a bubbler, then a dryer, then the solvent with product, then a scrubber, (uh , a bubbler through charcoal and soda water, container covered carefully with soda water towels.) all propelled by a small aq smell, no muss, no fuss...

turn it on and get your vac filters ready, you might have time to smoke a cigarette...if you have lots of solvent etcetera

farmer style gassing is for the birch crowd, more power to all who share their improvements, method described above is ridiculously simple, easy, and clean, disposal of acid mix only nuisance about it.wink
(Ubiquitous Precursor Medal Winner)
01-21-02 04:35
No 258837
      Re: Best Method for Hydrochloric Acid Gas  Bookmark   

Argox is right. His way is best.

turning science fact into <<science fiction>>