How to form Ammonium Chloride crystals?

[chochu3]

I tried making some NH4Cl and a bunch of it turn into gas when HCl and NH4OH was added. So then I tried a new batch this time adding ice so as to minimize the formation of NH4Cl gas. This work pretty good. Then I went to heat up the flask as to recover my crystals. After a while the formation of HCl started to stink up the room. This has happened many times trying to accelerate the formation of crystals using heat, I remember reading a book and it saying this happens. so the last time I let it sit their in the sun for two days. The mixture was cloudy so I added to the freezer. I left it in there to long and the mixture was frozen. After letting it thaw out it the apperance of crystals were at the bottom.
What is the best way to recover my crystals from this mix.

[Bugger]

You could filter them out from the cold mixture, using a funnel with filter paper, and preferably applying a vacuum with a Buchner funnel (usually porcelain) and a conical vacuum flask attached to a tap, but much of it would be left in solution. Because it is highly soluble, after the reaction it would be as well to slowly concentrate the solution to dryness, if it is desired to recover all the product.

BTW The formation of NH4Cl from aqueous NH3 and HCl is fairly exothermic, which could result in loss of its constituents without cooling and slow addition of one to the other. It sublimes at moderate temperatures, and decomposes at 350ºC. Known as sal ammoniac, it is used in dry-cell batteries, in medicine as an expectorant, and in electroplating.

[FUTI]

I would prefer sublimation than trying to crystalise it out of water. :(

Maybe if you pass gasseous ammonia and HCl in methanol you get better result when you combine those two solutions. Only obstacle is that HCl can dissolve to maybe 7% and NH3 as high as 20% (or something). At least you can cool down that solution without freezing. :p

[Jome skanish]

How about adding something to precipate the NH4Cl, like one could do with KNO3 and etanol/IPA/acetone. If the salt is isoluble in one of these or some other water-miscible solvets one could add the solvent to the water and then simply filter NH4Cl out.

Just my 2 oere!

[kurtz]

Perhaps your pH testing is not so good? I've made NH4Cl a few times in large amounts to obtain NH3 from crappy grocery store ammonia - and had no problems boiling away most of the water. Only a faint smell of ammonia, undetectable from a few feet away, and no noticable HCl. Crystallized very nicely, quickly forming crunchy white crystals, so I'm thinking that something is wrong with your chemicals or process.

The mixing of the two, giving a NH4Cl fog, that was the only unpleasantness I've had. If you stop boiling when a scum forms, there should be no problem.

[brother john]

I've made ammonium chloride using "Crystal Clear Ammonia" from the grocery store. It contains no soap or other additives. Muriatic acid was from the hardware store. The method used was real low tech. I put ammonia to the 4 cup mark in a 12 cup coffee pot. Then, while stirring, I added the muriatic acid until I figured it was enough. Stopped stirring & let it set for a few minutes. The container warmed-up some from the reaction. Not hot just warm. It smelled of acid so I stirred & added more ammonia. The acid fumes raise hell with the metal in my shop/lab so I tend to keep this type of reaction slightly basic since it was cold outside & the evaporating was to be done inside. Well, it smelled too ammonia so I had to add a little more acid then a little more ammonia until I was finally satisfied. I managed to accomplish this without running out of room in the container though it was cutting it close. This is a good lesson on why a person should learn stoichiometric compounding. At least I didn't overflow it this time. Each addition needs to be done with stirring to mix things good, then let sit awhile for the reaction to complete. I put it on a hot plate to simmer/slow boil with a small fan placed to help the steam escape the pot instead of condensing & running back down into what I'm working on evaporating. Oh, I put a 5 inch square X 1/4 inch plate of aluminum on the hot plate to give the bottom of the coffee pot a more even heat. Haven't busted a pot since adding it. The water was evaporated until crystals were covering the surface. It was allowed to cool to 50*F which at the time was "room temperature". A refrigerator would do fine. The solution was slowly poured off into another coffee pot leaving the crystals to be helped out of the pot onto a glass pie plate for drying. This was repeated until the solution is gone. The pie plate was then put on the hot plate at a very warm temp , the fan blowing the steam away whilst a stirring around of the crystals is done until dryness is achieved. Using grocery store ammonia gives a lot of water to steam away but the yield was decent & it kept me amused. The ph testing on this low tech lab can be a nose job. If it smells acid, it is. If it smells ammonia, it's basic. Aim for a slight ammonia odor. That will denote a small amount of unreacted ammonia. If it smells like water you're either exactly at the point of having reacted all the active ingredients or your nose has burned out.

[kurtz]

Better expand on my earlier post, since it hasn't been mentioned: all of the 3-6% grocery ammonias around here contain soap. You get a choice of ammonias that say that they have soap, and those that don't say so - but do contain it. I stopped boiling a few times, cooling to room temp, precipitating a soft waxy solid. Filtered out well with coffee filters. It is not a small amount, but not much trouble to get rid of.

Not knowing what salts these soaps are, this precipitate might well be a fatty acid, and there might be a small amount of some unwanted cation in the ending salt. Of course one should recrystallize.

[chochu3]

Thank you all for the replies.
I let my mass of compounds sit for about two weeks and now I see it has become full of crystals, I would like to find a fatser method to which this can be done, I like the one of using methanol and adding the gasses directly. Will try this one out some time and get back with my results as for the adding the solutions directly, I wil retest to see if it's a pH problem.

[anchorpad]

I was wondering if you could do like this to form NH4Cl on a easy way.
I realised that I wasn´t able to explain it with my bad english so i drawed a picture instead. :D

http://www.karlan.se/~daniel/imgs/skiss.jpg

The idea whit this is to avoid that the fumes from HCL and NH3 to be free in the house.

[FUTI]

HM...what I mean in the previous post is that you make saturated solution of ammonia in methanol in one flask, then make saturated solution of HCl in methanol in second flask and then mix the solution together. Be carefull since it can make fountain effect even when single gas is pass through at low pressure and can certainly make problem if you buble both gas in the same flask.

[FlaAlchemist]

This method won't make such a mess

Concentrated solutions of
Ammonium Sulfate + Calcium Chloride = Ammonium Chloride + Calcium Sulfate

Calcium Sulfate precipitates out of the solution , leaving the ammonium chloride in solution. Evaporate the solution and get Ammonium Chloride. :cool:

[FUTI]

I agree with FlaAlchemist that his method is the easiest way to NH4Cl. I proposed the different method because I thought that high purity is an issue here. Both will work, let us know what is your favorite way...and chochu3 why on earth you need it? I hope it is not the coughing problem.