Sciencemadness Discussion Board

Making ammonium carbonate

CHRIS25 - 20-5-2012 at 10:35

So I bubble carbon dioxide through water to make carbonic acid and then use this acid to let fumes from 26% ammonia (in Water) to bubble through the acid. NH3 + H2CO3 = H2O + NH3CO2.../Is there another way please? Knowing me I would make a mess of things and I don't have the right equipment to do this sort of thing.

I was thinking taking calcium carbonate and Ammonium hydroxide the 26% ammonia in water (although I have read that there is no such thing as ammonium hydroxide), to get calcium hydroxide and ammonium bicarbonate?

Adas - 20-5-2012 at 10:55

Ammonium sulfate + NaHCO3 (for ammonium hydrogen carbonate) or Na2CO3 for diammonium carbonate. But both of them are VERY unstable and decompose to CO2, NH3 and water, because H2CO3 is a very weak acid and NH3 is a weak base.

barley81 - 20-5-2012 at 11:16

Ammonium carbonate is not very unstable. Sure, it sublimes and can decompose, but it is a solid at room temperature. There is a large container of it at my school. It has a strong smell of ammonia.

EDIT: This kind of "ammonium carbonate" in bottles is not actually ammonium carbonate.

If you use sodium salts to make ammonium carbonate/bicarbonate, you will have a hard time separating out the ammonium salts. Bubbling CO2 is probably a better way. The problem with this is that you cannot easily control how much you bubble in, and you may get a mixture of the bicarbonate and carbonate. (This is only a thought. No reference, so this statement may not be creditable.)

[Edited on 21-5-2012 by barley81]

CHRIS25 - 20-5-2012 at 13:53

Hi, I don't have ammonium sulphate. But how about Sodium carbonate which has a solubility of 21g @ 20c per 100ml and ammonium chloride which has a solubility of 37g @ 20c per 100ml. Or How about heating Ammonium chloride and calcium carbonate, mix the result with alchohol, then filter and heat the alchohol to evaporation?

[Edited on 20-5-2012 by CHRIS25]

Polverone - 20-5-2012 at 16:21

Don't try to precipitate it from solution. You can instead prepare it by mixing sodium carbonate and ammonium chloride moistened with a little water in the bottom of a long-necked glass bottle. Keep the top of the bottle cooled and partially closed, e.g. by lightly screwing on a cap and wrapping a wet cloth around the neck. Heat the bottom of the bottle gently on a hot plate or in a water bath. Ammonium carbonate will condense in the cool neck of the bottle as a dense deposit where it can be broken into chunks and removed with a thin bladed knife or similar tool.

This "ammonium carbonate" is not a pure, single chemical substance, but neither is or was the current commercial or historical product. If you are trying to make your own smelling salts or obtain a material for replicating historical art/craft materials, it should be fine.

barley81 - 20-5-2012 at 16:35

http://www.sciencemag.org/content/140/3572/1205.abstract

Polverone is right; reagent grade ammonium carbonate consists of ammonium "bicarbonate-carbamate".

CHRIS25 - 20-5-2012 at 22:09

Polverone, there is no way I would have discovered this - thankyou - I look forward to trying it tomorrow - I am making it as part of an ingredient for an old patina recipe. Although the only long wide necked glass I have does not have a lid, I suppose I could make one no problem - plastic is fairly inert against Amm.Carbonate I assume. Barley, yes I had read that this decomposes to Amm.bicarbonate, also it is incredibly soluble, at 100grams in 100 mils of water. But I confess I am a bit confused here because last night I was reading that it actually decomposes in water, still have to check this out further as i was too tired to go on.

Thanking you both for your help - appreciated as always.

I have just come accross something troubling: I read that the formation of Ammonium Carbonate can be very stressful on glass and that it was preferable to use a metal container? Since this was a chemical website I assume they are referring to borosilicate in their comments. Any thoughts here?
http://www.zoklet.net/totse/en/technology/science_technology...

[Edited on 21-5-2012 by CHRIS25]

[Edited on 21-5-2012 by CHRIS25]

Have a problem here with Sodium Carbonate. I have wash crystals and these are "sodium carbonate decahydrate greater than 30%" This is 286 g/Mol. But what is the rest then, for it seems that It is impossible now to get an accurate g/mole for this product.

[Edited on 21-5-2012 by CHRIS25]

hissingnoise - 21-5-2012 at 09:16

Quote:
Polverone, there is no way I would have discovered this . . .

It ain't called sal volatile for nothing!


CHRIS25 - 21-5-2012 at 09:28

Quote: Originally posted by hissingnoise  
Quote:
Polverone, there is no way I would have discovered this . . .

It ain't called sal volatile for nothing!



Yes maybe I should have fainted and then a great discovery would have been made!

CHRIS25 - 21-5-2012 at 09:48

Have looked everywhere finding MSDS info for Dri-Pak soda crystals. It seems that the other 70% of the ingredients are top secret since all the documentation that I have sourced says the same old boring clap-trap: Sodium carbonate greater than 30%...Ugh! Irritating...

just had an idea, if I put sodium carbonate into alchohol and whatever does not dissolve could be the purer form?

[Edited on 21-5-2012 by CHRIS25]

Polverone - 21-5-2012 at 12:03

Is sodium bicarbonate available in pure form where you live? If it is, you can place it in a pan on a stove and heat the dry powder while stirring it. Carbon dioxide and water vapor will be driven off with visible bubbling/churning in the powder and you will be left with pure, dry, fine-grained sodium carbonate that it is easy to handle and calculate stoichiometry with.

CHRIS25 - 21-5-2012 at 13:48

Quote: Originally posted by Polverone  
Is sodium bicarbonate available in pure form where you live?.


Hi polverone, yes I have plenty of that but I have 2kg of this washing soda and was happy to waste this stuff, it was so cheap. It is just a pity that I have to use sodium bicarbonate, I bought the darn stuff (Wash soda) because everyone ranted and raved about how it was sodium carbonate, knowing that I would find it useful. Ah well. Still I would be so interested in knowing what that other 70% is; I think that there could be sodium silicate and potassium and even bicarbonate mixed in, but not sure. Your american hammer and something is apparently pure carbonate I think.

hissingnoise - 21-5-2012 at 13:51

Polverone, I think there's hardly a kitchen in Ireland that's washing-soda free . . .
And the weight of the bought crystals is made up mostly of water of hydration!



ScienceSquirrel - 21-5-2012 at 14:19

We can buy the anhydrous salt here. It does not dissolve so quickly but it is easier to handle.

hissingnoise - 21-5-2012 at 14:30

Don't let it effloresce is the seller's avaricious motto here . . .
Bastards!


Lambda-Eyde - 21-5-2012 at 14:47

The washing soda I buy here ("krystallsoda") also appears to be anhydrous: It didn't lose any weight after heating at >100 C for a few hours.

CHRIS25 - 23-5-2012 at 09:47

Hallo, have just finally found the ingredients if Dri-Pak Soda crystals:

Sodium carbonate >30%; Magnesium Hydroxide (no percentage given); Silica (no percentage given); Tiny percentage of anti-caking agents;

That's the best I can find. The hammer you have in USA (not availbale outside USA) is apparently 85% Sodium Carbonate. I would like to know why they use these other ingredients though - the anti caking stuff would be to prevent clumping I presume and the silica to absorb moisture so as to keep the decahydrate in tact? What about the magnesium hydroxide?

cyanureeves - 23-5-2012 at 15:51

arm and hammer soda wash is 85% carbonate and 15% water so its pretty pure. that is what one msds read.

White Yeti - 25-5-2012 at 12:50

I've tried to make ammonium bicarbonate, but I've only been met with failure so far. When you try to crystallize it out, it decomposes into ammonia gas and carbon dioxide most of the time. One time I got odourless crystals come out of solution. I might try again by subjecting chilled ammonia solution to a very high pressure of carbon dioxide gas. Reacting sodium bisulphate with sodium bicarbonate allows for a steady stream of carbon dioxide, so I might try to generate and use the carbon dioxide in the same vessel.

CHRIS25 - 25-5-2012 at 15:14

I have not tried it yet but Polverones method has good advice

Fantasma4500 - 8-3-2013 at 10:19

im thinking about doing this as i see an idea or well an use for (NH4)2CO3 when making AN (relatively pure) and even for other ammonium salts with a byproduct that can be filtered off
Cu(NO3)2 + (NH4)2CO3 > NH4NO3 + CuCO3*Cu(OH)2
nonbalanced, relatively easy to get stuff

my idea of making (NH4)2CO3 is following
(NH4)2SO4 + CaCO3 > CaSO4 + (NH4)2CO3
CaSO4 is quite insoluble, so the procedure is pretty selfexplanatory except for the nessecary heat control aswell as perhaps using dessicant / large surfaces to decompose the decanted liquid to get the solid ammonium carbonate..

AJKOER - 8-3-2013 at 14:23

The action of aqueous ammonia on aqueous MgSO4 (Epsom salts dissolved in water) produces a very white fine precipitate. My take on the reaction:

NH3 + MgSO4 + 2 H2O --> Mg(OH)2 (s) + NH4HSO4
---------------------------------------------------------------------

Now, the use of Ammonium bicarbonate is perhaps preferable, in my opinion, in the reaction employing Ammonium sulfate:

(NH4)2SO4 + CaCO3 --> CaSO4 (s) + (NH4)2CO3

as CaCO3 solubility increases the more acidic the medium, and Ammonium hydrogen sulfate is more acidic than Ammonium sulfate.

NH4HSO4 + CaCO3 --> CaSO4 (s) + NH4HCO3