Sciencemadness Discussion Board

Ammonia Gas Generator

mericad193724 - 17-1-2007 at 06:20

I would like to make some concentrated ammonia solutions. The Ammonia I get from the supermarket for cleaning is VERY dilute. I read that an ammonium salt and sodium hydroxide heated in an aqueous solution will produce ammonia gas.

Would Ammonium Nitrate and Sodium Hydroxide be a dangerous?...Ammonium nitrate is a strong oxidizer which can explode when heated to dryness so I just want to make sure it is safe to heat a concentrated Ammonium nitrate solution with hydroxide. (Drain opener and Ice pack).

Thanks,

Mericad

Jdurg - 17-1-2007 at 06:26

Quote:
Originally posted by mericad193724
I would like to make some concentrated ammonia solutions. The Ammonia I get from the supermarket for cleaning is VERY dilute. I read that an ammonium salt and sodium hydroxide heated in an aqueous solution will produce ammonia gas.

Would Ammonium Nitrate and Sodium Hydroxide be a dangerous?...Ammonium nitrate is a strong oxidizer which can explode when heated to dryness so I just want to make sure it is safe to heat a concentrated Ammonium nitrate solution with hydroxide. (Drain opener and Ice pack).

Thanks,

Mericad


No, Ammonium Nitrate will not explode if heated to dryness. It will decompose into nitrogen oxides and other nasty stubstances as the temperature rises, but you're not going to set off a massive explosion by heating up a pile of NH4NO3. I honestly have no idea how that myth got propagated and why it still exists to this day. Ammonium Nitrate requires a fairly substantial shock to get it decomposing explosively. Hence why blasting caps are used.

UnintentionalChaos - 17-1-2007 at 06:41

That would work in theory, though I have never done it before. Afterward, you are left with NaNO3 which you could mix with KCl road salt (have to look for the right salt) and recrystallize for KNO3. It should be a sin to waste nitrates. :P

Edit: issues with CuSO4 theory. Hydroxide becomes an issue.

[Edited on 1-17-07 by UnintentionalChaos]

YT2095 - 17-1-2007 at 08:15

KOH and AN mixed in soln is exactly how I make mine also, it requires gentle heat and a Very cold capture vessel, but other than that, it`s about as simple as it gets.
the KNO3 is great for feeding Chili plants with too :)

roamingnome - 17-1-2007 at 10:05

i hope to use ammonium sulphate, this should work as well, heating with CaO right?

nitrate may be exspensive, ammonium sulphate is well, certain dirt is actaully more pricey....

garage chemist - 17-1-2007 at 10:39

I make my ammonia gas by boiling ammonia solution under reflux, the gas comes out at the top of the condenser.
The temperature of the boiling solution is measured and slowly approaches 100°C as the NH3 is driven out. As it reaches 100°C, all ammonia has been expelled.
I think this is the most economic method, but for dilute NH3 solutions you will need a large boiling flask so that enough NH3 can be evolved before having to change the solution.

Sauron - 17-1-2007 at 10:55

FYI ammonium nitrate plus NaOH as solid mixture is the simplest and oldest gunsmith's blueing salts mix for the "blueing" of steel parts of firearms. This is done at a high temperature in an extremely concentrated solution and my recollection is that when this is mixed with offgases a lot of NH3. Not a pleasant process to conduct, it is done in black iron tanks heated with long burner tubes fed from LPG tanks. Gunsmiths often face serious burns from hot concentarted caustics. There are various proprietary modifications to the simple AN/lye mix for blueing some alloys, even stainless steel. Brownell's the the suplier in USA.

joeflsts - 17-1-2007 at 11:33

Quote:
Originally posted by mericad193724
I would like to make some concentrated ammonia solutions. The Ammonia I get from the supermarket for cleaning is VERY dilute. I read that an ammonium salt and sodium hydroxide heated in an aqueous solution will produce ammonia gas.

Would Ammonium Nitrate and Sodium Hydroxide be a dangerous?...Ammonium nitrate is a strong oxidizer which can explode when heated to dryness so I just want to make sure it is safe to heat a concentrated Ammonium nitrate solution with hydroxide. (Drain opener and Ice pack).

Thanks,

Mericad


I've had good luck with gently heating Ammonium Chloride with Calcium Hydroxide in water.

Joe

YT2095 - 17-1-2007 at 11:37

NaOH (as he mentioned) does indeed work ;)

the driver for the calcium reaction is very weak, if it was ammonium Sulphate or Carbonate it should work like crazy :)


[Edited on 17-1-2007 by YT2095]

woelen - 17-1-2007 at 11:47

I have made NH3 gas (humid) by mixing solid (NH4)2SO4 with solid NaOH, crushing the mix somewhat, and then adding a few drops of water, such that you get a white wet mess. Gentle heating produces almost pure NH3-gas which is quite humid though. This gas can be absorbed in a receiver flask, filled with distilled water.

I also have done this with NH4Cl instead of (NH4)2SO4. It works equally well.
Another method I have is heating (NH4)2CrO4 very gently. It leaves behind (NH4)2Cr2O7 and produces lots of ammonia and water vapor.
For someone, less rich in chemicals, probably the ammonium sulfate or ammonium nitrate route is best.

guy - 17-1-2007 at 13:56

Wouldnt using a carbonate be better? NaOH is too precious nowadays.

DeAdFX - 17-1-2007 at 14:17

One could also use Urea and the enzyme Urease. The greatest difficulty in this is isolating the enzyme.

roamingnome - 17-1-2007 at 14:59

Department of Dental Pathology and Therapeutics, University of Illinois, College of Dentistry, Chicago, Ill.



Bacteria capable of producing urease were found in 92.8% of 405 salivary samples from 82 patients. In 65.4% of the samples, appreciable quantities of urease were produced.



awsome ill just spit on my piss

YT2095 - 18-1-2007 at 02:27

Quote:
Originally posted by guy
Wouldnt using a carbonate be better? NaOH is too precious nowadays.


you`de make ammonium carbonate that way though, and although it does break down with heat it`s extra work.
unless you had Ammonium carbonate to start with, then almost any hydroxide will convert it, Calcium hydroxide would be great to use then.

garage chemist - 18-1-2007 at 05:29

Ammonium carbonate decomposes in solution by itself, no base has to be added. But what evolves is a mix of CO2 and ammonia.

Ammonium chloride and nitrate can be converted to ammonia using calcium hydroxide in aqueous suspension, the only difference being that you have to heat stronger than with NaOH.
So the NaOH can be replaced by the cheaper Ca(OH)2.

franklyn - 18-1-2007 at 09:22

Quote:
Originally posted by mericad193724
I would like to make some concentrated ammonia solutions. The Ammonia I get
from the supermarket for cleaning is VERY dilute. I read that an ammonium salt
and sodium hydroxide heated in an aqueous solution will produce ammonia gas.

I don't understand your meaning of dilute unless you only have access to
household cleaners which only contain some ammonia as an ingredient.
Commercially available clear ammonium hydroxide available in supermarkets is
a solution close to saturated. To expell the gas you only need to mix in quick lime
CaO if Na2O is a problem for you. This is quite vigorous and should be done in the
open or you may have to evacuate from indoors if there is a leak so start small.

Here is a chemists proceedure in detail please observe the warnings
ammonia inhalation can certainly kill you.

http://designer-drug.com/pte/12.162.180.114/dcd/chemistry/el...

.

Jdurg - 18-1-2007 at 15:56

Ummmm..... the ammonia solutions you get in a grocery store are typically around 3% which is so incredibly far from saturated. You need a great deal of that solution in order to make some concentrated ammonia solutions.

garage chemist - 18-1-2007 at 16:20

In France you could buy 20% ammonia for less than 1€ per Liter. I bought four liters for filling my gas bottle (using a fridge compressor). 500ml liquid anhydrous ammonia for less than 4€, that was a really good idea. The gas bottle is still about half full.

Sadly the 20% has now been replaced with 12%, which costs the same.:mad:
In germany the OTC ammonia solution is 9%, and it costs about 4€ per liter. This is not worth the money at all. Better buy the 25% stuff over the internet.

guy - 18-1-2007 at 18:31

Quote:
Originally posted by garage chemist
Ammonium carbonate decomposes in solution by itself, no base has to be added. But what evolves is a mix of CO2 and ammonia.

Ammonium chloride and nitrate can be converted to ammonia using calcium hydroxide in aqueous suspension, the only difference being that you have to heat stronger than with NaOH.
So the NaOH can be replaced by the cheaper Ca(OH)2.


First you would form NH3 and a bicarbonate ion. Further reation of the bicarbonate with ammonium will make CO2 and NH3.

So if you dont want CO2, then use more carbonate.

YT2095 - 19-1-2007 at 01:34

another good tip when making ammonia soln is to use an upside down funnel just a little way under the surface of the receiver vessels liquid.
NH3 is Very soluble in water and you risk Suck-back into your reaction vessel.
using a funnel gives you a greater surface area of gas liquid interface and if suck-back starts if can only progress a little way up inside the funnel before the seal breaks and the releases the liquid again.

it`s really worth that little bit extra time and effort to do :)

unionised - 21-1-2007 at 04:50

"No, Ammonium Nitrate will not explode if heated to dryness. It will decompose into nitrogen oxides and other nasty stubstances as the temperature rises, but you're not going to set off a massive explosion by heating up a pile of NH4NO3. I honestly have no idea how that myth got propagated and why it still exists to this day. Ammonium Nitrate requires a fairly substantial shock to get it decomposing explosively. Hence why blasting caps are used. "
My best guess as to why this idea still exists is that it seems to be true.
For example see this
http://www.unep.fr/pc/apell/disasters/toulouse/home.html
and for another 16 examples see this
http://en.wikipedia.org/wiki/Ammonium_nitrate
What I don't understand is why people insist that it doesnt happen.

OTOH, in the circumstances we are talking about it isn't a problem The stuff will give off the ammonia as soon as it gets warm and then there's no fuel for the reaction.

Aqua_Fortis_100% - 21-1-2007 at 06:04

Quote:
originally posted by garage chemist:
Ammonium chloride and nitrate can be converted to ammonia using calcium hydroxide in aqueous suspension, the only difference being that you have to heat stronger than with NaOH.
So the NaOH can be replaced by the cheaper Ca(OH)2.


i have NO NH4NO3 or NH4Cl, so my "usual" generator of NH3 gas is (NH4)2SO4/NaOH mix... i tried make NH3 via ammonium sulphate salt and Ca(OH)2 (really MUCH cheaper than NaOH).. but only a weak smell of NH3 was observed and the reaction stops quickly... i think which should be the insoluble CaSO4 formed.. but i haven't tried heat this.. will work if heating this ???
thanks

Organikum - 22-1-2007 at 05:05

Quote:
Originally posted by DeAdFX
One could also use Urea and the enzyme Urease. The greatest difficulty in this is isolating the enzyme.

One could also just heat the urea. IIRC up to about 180°C only NH3 is produced.

/ORG

YT2095 - 22-1-2007 at 09:32

Avoid Alcohol!

Jdurg - 22-1-2007 at 13:41

Quote:
Originally posted by unionised
"No, Ammonium Nitrate will not explode if heated to dryness. It will decompose into nitrogen oxides and other nasty stubstances as the temperature rises, but you're not going to set off a massive explosion by heating up a pile of NH4NO3. I honestly have no idea how that myth got propagated and why it still exists to this day. Ammonium Nitrate requires a fairly substantial shock to get it decomposing explosively. Hence why blasting caps are used. "
My best guess as to why this idea still exists is that it seems to be true.
For example see this
http://www.unep.fr/pc/apell/disasters/toulouse/home.html
and for another 16 examples see this
http://en.wikipedia.org/wiki/Ammonium_nitrate
What I don't understand is why people insist that it doesnt happen.

OTOH, in the circumstances we are talking about it isn't a problem The stuff will give off the ammonia as soon as it gets warm and then there's no fuel for the reaction.


Well did you notice some common things apparent in all of those descriptions? Either some type of priming explosive hit the mass of ammonium nitrate which would put the required detonation wave through the mass, or the incident involved HUGE quantities of the compound which will instantly alter it's properties. The greater the mass you have, the higher the likelihood of localized "super-dense" areas. E.G., if you have a massive quantity of feathers piled on top of each other, the feathers in the very middle will be locally MUCH more dense than those on the edge.

When you deal with explosives, this very close proximity caused by the heavy stacking of ammonium nitrate crystals causes the required detonation wave going through the mass to be less and less and less. (Since when the resulting detonation velocity from the tiny bit of NH4NO3 goes "boom", it will be able to interact with a lot more NH4NO3 and set off a lot of little tiny "booms". A lot of little tiny "booms" is just as destructive as one big "boom").

In the quantities of NH4NO3 that people have lying around their labs, I just don't see the ammonium nitrate detonating unless you really work hard at getting it to do so.

YT2095 - 22-1-2007 at 13:58

JEANBERGIAN I rest my case :)

YT2095 - 22-1-2007 at 14:02

to Elucidate...
Quote:
Originally posted by JEANBERGIAN
If I had a cooling sistem up to the job, this would be my pet.Do you know yow many B.Units need to do ,say, 4
ounces? At 70 / 80F ?
Urea is cheap and simple to get.


reads Alc or Drug induced .

12AX7 - 22-1-2007 at 14:14

I think the most salient point from almost all those explosions is that excess AN, in the exploding heap, was thrown significantly far and did not itself detonate. A pretty shitty explosive if a sizable fraction (like, more than half) doesn't explode!

Tim

S.C. Wack - 22-1-2007 at 16:08

from here

Ammonium nitrate, in solid or molten
form or in solution, is a stable compound
and generally is difficult to explode.
Ammonium nitrate may explode, however,
when exposed to strong shock or to high
temperature under confinement. In a large
quantity of ammonium nitrate, localized areas
of high temperature may be sufficiently confined
by the total quantity to initiate an explosion. The
explosion of a small quantity of ammonium
nitrate in a confined space (e.g., a pipe) may
initiate the explosion of larger quantities (e.g.,
in an associated vessel).
Contaminants may increase the explosion
hazard of ammonium nitrate. Organic materials
generally will make ammonium nitrate
explosions more energetic. Ammonium nitrate
may be sensitized by certain inorganic
contaminants, including chlorides and some
metals, such as chromium, copper, cobalt, and
nickel. As ammonium nitrate solution becomes
more acidic, its stability decreases, and it may
be more likely to explode.
Low density areas, such as bubbles, in molten
ammonium nitrate or solutions, also may
increase the possibility of an explosion and
enhance the propagation of an explosion.
Ammonium nitrate by itself does not burn, but
in contact with other combustible materials, it
increases the fire hazard. It can support and
intensify a fire even in the absence of air. Fires
involving ammonium nitrate can release toxic
nitrogen oxides and ammonia. A fire involving
ammonium nitrate in an enclosed space could
lead to an explosion. Closed containers may
rupture violently when heated.

Engager - 2-2-2007 at 11:34

Any soluble salt of ammonia + NaHCO3/Na2CO3, just mix solutions and boil them. That will result in ammonia gas and corresponding salt of sodium, for example:

Na2CO3 + 2NH4Cl = (boiling) => 2NaCl + 2NH3 + H2O + CO2

Ammonia is dried by passing colunms with KOH and is liquified/freezed in U shape tubing cooled by dry CO2 (dry ice) / acetonе mixture (-90C temperature could be reached).

HenningBasse - 5-2-2007 at 22:25

can someone help me out with this??

http://www.sciencemadness.org/talk/viewthread.php?tid=7695

is just about making ammonia from urea

thx in advance

MagicJigPipe - 11-3-2008 at 16:25

The bottom line is NH4NO3 is difficult to detonate even with a blasting cap and a booster charge ON PURPOSE. I'm thinking these incidents only happen with HUGE quantities of NH4NO3 and I believe it presents virtually zero risk to the home experimenter.

not_important - 11-3-2008 at 18:21

Quote:
Originally posted by Engager
Any soluble salt of ammonia + NaHCO3/Na2CO3, just mix solutions and boil them. That will result in ammonia gas and corresponding salt of sodium, for example:

Na2CO3 + 2NH4Cl = (boiling) => 2NaCl + 2NH3 + H2O + CO2



However using a carbonate leads to the formation of ammonium carbonates and carbamates in the takeoff tubing. For some applications this is not a problem, a solution of the gases can be considered a solution of ammonium carbonate, as is used in some inorganic analysis. But if the goal is strong aqueous ammonia, or liquid ammonia, you had best use a hydroxide rather than a carbonate.