Sciencemadness Discussion Board - Ammonium Carbonate and Ammonia Vapor ?

Ammonium Carbonate and Ammonia Vapor ?

BaFuxa - 12-2-2018 at 09:39

Hi,

Just attempted making some ammonium carbonate.

I bubbled CO2 into aqueous ammonia, from calcium carbonate ( chalks ) and HCL. I noticed that a heavy ammonia (?) vapor spreading over the surface.

Any idea what this is ? To me the reaction is 2NH3 (l) + CO2(g) + H2O(l) -> (NH4)2 CO3

Why do I get this vapor, is it not supposed to be reacting with the CO2 ? For comparison I bubbled air and expired into the solution of aqueous ammonia and nothing happened.

Edit : photo added.

[Edited on 12-2-2018 by BaFuxa]

[Edited on 12-2-2018 by BaFuxa]

JJay - 12-2-2018 at 09:39

Does it look like smoke?

BaFuxa - 12-2-2018 at 09:42

Yes it does.

By the way how do you insert photos ( "Please enter the URL to the image you wish to insert" : how to do that ?). ?

happyfooddance - 12-2-2018 at 09:43

What temperature is your solution, and what concentration NH3? If you keep it cold you will have better results. Ammonium carbonate leaves solution when heated, and the ammonia smell can be very, very strong.

BaFuxa - 12-2-2018 at 09:49

Temperature : RT ( 15 and 20° C), the NH3 concentration is 13%.

I noticed that this vapor crystallized over the inside of the flask as well.

Had no idea aqueous ammonium carbonate was such a crazy volatile

Vosoryx - 12-2-2018 at 09:56

Photos can be inserted by attaching the file below the text reply box. It took me a while to figure out.

The photos have to be saved to a drive in order to do this, they can't be copied in.
And, of course, the size limits also apply.

The "Insert image" button you used was for images online.

happyfooddance - 12-2-2018 at 10:21

Quote: Originally posted by BaFuxa

Temperature : RT ( 15 and 20° C), the NH3 concentration is 13%.

I noticed that this vapor crystallized over the inside of the flask as well.

Had no idea aqueous ammonium carbonate was such a crazy volatile

Sounds like it's working then.

Add a little crushed ice, and add your CO2 slowly. You SHOULD scrub residual HCl from your CO2, but if you go slowly it won't be a problem, unless chloride contamination is a problem for you.

Ammonium carbonate can be very bad. I have had a couple experiences that have led me to take great caution with this compound. Make sure your outlet and all your tubing stays clear! When a layer cakes on the wall and you can't see inside, how do you know that it isn't a closed system?!?

Edit: adding CO2 is basically sparging the solution, that's why you want to do it slowly. Also, it isn't so much that ammonium carbonate (which is really not that, but a variety of complexes...) is volatile, but that neutral CO2 and NH3 are very volatile, and these things find ambient water ( of which there is a lot of sitting over a flask of water) marry each other and crystallize.

[Edited on 2-12-2018 by happyfooddance]

MrHomeScientist - 12-2-2018 at 11:51

Looks similar to ammonium chloride smoke produced when HCl and NH₃ vapors meet. I think happyfooddance is right in that this is a similar reaction between gaseous CO₂ and NH₃ above the solution.

[Edited on 2-12-2018 by MrHomeScientist]

NEMO-Chemistry - 12-2-2018 at 12:31

I would say HCl is getting through, Ammonia and HCl smoke ALOT

. Actually while not recommended for a lab, i think some people have it in confectionery!!

HCl and Ammonia is how I tested the fan in my fume hood. That gave small crystals as well.

happyfooddance - 12-2-2018 at 13:04

Quote: Originally posted by NEMO-Chemistry

I would say HCl is getting through, Ammonia and HCl smoke ALOT

. Actually while not recommended for a lab, i think some people have it in confectionery!!

HCl and Ammonia is how I tested the fan in my fume hood. That gave small crystals as well.

In european licorice, ammonium chloride is very common. I can't think of a single other instance it is used. Ammonium carbonate is quite common in specialty recipes; originally it was obtained by the dry distillation of deer antler: https://en.m.wikipedia.org/wiki/Hartshorn

semiconductive - 12-2-2018 at 13:11

Quote: Originally posted by happyfooddance

Quote: Originally posted by BaFuxa

Awsome. I tried to make ammonium carbonate before, and used 90PSI CO2 (dry ice goes 800PSI in an old scuba tank with a regulator)... everything went into solution in a champaign bottle. There was no smoke on top, even though the outside temperature was 10C in winter. Now that I see the reaction happens in the air space above the liquid ... and that fast addition of CO2 is a mistake; I have a pretty good idea why my attempt failed.

It seems to me, that this experiment might be better done by heating an ammonia solution and carbonate solution in separate flasks and then piping the gasses over to a third flask that is kept very cold on bottom (ice underneath?). Then the crystals would only want to form on the bottom of the flask where it's cold and dry enough to be stable. That might also solve the problem of keeping the product from dissolving in the ammonia solution that has a lot of water ... and is hard to separate.

I was hoping to use ammonium carbonate to replace wax in lost wax casting. Since NH4O3.??H2O leaves no residue when heated, and doesn't produce carbon monoxide, it shouldn't hurt canthal heating elements like burning wax does. Ammonia's not fun, but it's better than strong hot CO !

[Edited on 12-2-2018 by semiconductive]

JJay - 12-2-2018 at 13:49

Those are my thoughts as well. Ammonia salts can produce thick smoke even in very low concentrations when gaseous ammonia reacts with airborne acid anhydrides like HCl, SO2 and CO2.

happyfooddance - 12-2-2018 at 15:41

Quote: Originally posted by MrHomeScientist

Looks similar to ammonium chloride smoke produced when HCl and NH₃ vapors meet. I think happyfooddance is right in that this is a similar reaction between gaseous CO₂ and NH₃ above the solution.

[Edited on 2-12-2018 by MrHomeScientist]

It is very different though, I think, personally... When you boil an ammonium chloride solution, you don't (in my experience) get any solid forming over the solution. When you boil an ammonium carbonate solution, solids tend to condense above the solution: in the neck of the flask, in the condenser... It is very dangerous, really.

OP should be using some sort of vapor trap. I once converted. 1.5 mol ammonium nitrate to NaNO3 with sodium bicarbonate, outdoors on a hotplate (after my bad indoor experience), and standing about 20 feet away my eyes were burning.

zed - 12-2-2018 at 17:00

Well yeah. Snap your head back, it will.

Used to be called "Smelling Salts". Victorian fainting medicine.

https://en.wikipedia.org/wiki/Smelling_salts

[Edited on 13-2-2018 by zed]