Sciencemadness Discussion Board - ammonia gas

ammonia gas

maxenzo2 - 13-1-2015 at 08:19

Hi guys,today i have find out something i wasnt expecting,i wanted to see my potassium nitrate burn with sugar,just to see the reaction taking place nothing from the other world.I placed the mixture on my barbecue that still has some ash in it and a steel plate in the middle,i have light it up,but something weird happend,the ash and the burning chemicals mixed and something like a foam started to form instead of the carbon and other stuff that forms when sugar/kno3 burns.I was curious how the hell that happend,so i took a spoon and started breaking it,every time i broke it,it burned in the air not with flames(im not sure whats the word in english),i kept digging and a strong smell of ammonia strike me and i run,men i got scared,i know its not nitrogen dioxide(another toxic crap) because i smelled it before,it was ammonia.

Can you guys give an opinion on how that happend? im not sure,i know it probably was at the steel the ammonia formed but where did the hydrogen come from?! and how could it be formed without pressure?

i know this is nothing special i just didnt know it was possible something like that to happend,one thing is for sure i wont be burning any more kno3/sugar on top of a steel plate with ashes.

[Edited on 13-1-2015 by maxenzo2]

deltaH - 13-1-2015 at 08:32

This is very interesting maxenzo2. What was you sugar KNO3 mixture ratio?

Taking a stab in the dark here, but if you had too much sugar (it sounds like you did) then you would have created reducing conditions, like a gas flame where there is too much gas in the mix. This could hypothetically prevent nitrogenic compounds from forming nitrogen gas... that should otherwise have occurred.

We all know the well know oxidation of ammonia to nitric oxide, but perhaps nitrates can be reduced to ammonia under reducing conditions. Sugar is a powerful reductant at high temperature.

I don't even want to begin to speculate on the role of the ash here, but certainly you should do some more experiments on this. It might yield an important result!

[Edited on 13-1-2015 by deltaH]

Molecular Manipulations - 13-1-2015 at 08:50

That is quite interesting. If your potassium nitrate had some hydroxide ions in it, and if your "steel" plate was aluminum and if some water was present, then ammonia gas generation can be explained easily.
Aluminum can reduce nitrate to ammonia in the presense of hydroxide, perhaps carbon can too?
The ashes would have contained some hydrated potassium carbonate, maybe that could do it?

3 H₂CO + KNO₃ + K₂CO₃* 2 H₂O → 3 CO₂ + NH₄ + 3 H₂O + 1.5 K₂O

( H₂CO = empirical formula for sucrose, almost)

Of course this is all just sepeculation, could be completely off.

[Edited on 13-1-2015 by Molecular Manipulations]

Amos - 13-1-2015 at 08:59

Where did this potassium nitrate come from?

maxenzo2 - 13-1-2015 at 09:10

Quote: Originally posted by No Tears Only Dreams Now

Where did this potassium nitrate come from?

its from haifa greenhouse grade potassium nitrate,but its the first time this happend it didnt happend before in lots of occasion i burned it with sugar and other stuff and in some reactions,there is no traces of ammonium nitrate in it im sure of it,or else it would give off ammonia one time i tried to make sodium nitrate,the chemical reaction probably has something to do with the foam that formed and the steel plate on the bottom,since iron is used to make ammonia,i just find it weird because ammonia only forms in high pressure its weird,high quantity of hydrogen and so on.

my theory is urea was formed and with the temperature dissociated to ammonia, but it can be wrong for sure.

[Edited on 13-1-2015 by maxenzo2]

Bot0nist - 13-1-2015 at 10:43

Can you test the potassium nitrate for ammonium content? Maybe heat gently with a strong base and see if any ammonia is produced.

maxenzo2 - 13-1-2015 at 13:02

Quote: Originally posted by Bot0nist

Can you test the potassium nitrate for ammonium content? Maybe heat gently with a strong base and see if any ammonia is produced.

i already did it with sodium hydroxide,there was no ammonium nitrate in it,there was no smell of it,for example with calcium ammonium nitrate i did the same and released lots of ammonia,and the ammonia odor was in solution.

Edit: Another thing,i left a little bit of potassium nitrate open in contact with air for a day and didnt get any moisture,if ammonium nitrate or urea was present it would be traces of water in it,and it wouldnt create that much gas from the strong stench it came of that foam.

this is the potassium nitrate i have haifa potassium nitrate

[Edited on 13-1-2015 by maxenzo2]

[Edited on 13-1-2015 by maxenzo2]

[Edited on 13-1-2015 by maxenzo2]

aga - 13-1-2015 at 13:18

Quote: Originally posted by maxenzo2

I placed the mixture on my barbecue that still has some ash in it

What was the 'ash' ?

Obviously things other than Wood get burned in your barbecue, so what could the ash have contained ?

maxenzo2 - 13-1-2015 at 13:18

Quote: Originally posted by deltaH

This is very interesting maxenzo2. What was you sugar KNO3 mixture ratio?

Taking a stab in the dark here, but if you had too much sugar (it sounds like you did) then you would have created reducing conditions, like a gas flame where there is too much gas in the mix. This could hypothetically prevent nitrogenic compounds from forming nitrogen gas... that should otherwise have occurred.

We all know the well know oxidation of ammonia to nitric oxide, but perhaps nitrates can be reduced to ammonia under reducing conditions. Sugar is a powerful reductant at high temperature.

I don't even want to begin to speculate on the role of the ash here, but certainly you should do some more experiments on this. It might yield an important result!

[Edited on 13-1-2015 by deltaH]

im not sure,but im sure i used more sugar than kno3,the ammount was around 15grams.

maxenzo2 - 13-1-2015 at 13:20

Quote: Originally posted by aga

Quote: Originally posted by maxenzo2

I placed the mixture on my barbecue that still has some ash in it

What was the 'ash' ?

Obviously things other than Wood get burned in your barbecue, so what could the ash have contained ?

its hardwood charcoal its not wood,when i made the barbecue i have let burn till the end.And i lite the kno3/sugar not on top of the black ashes,but on the side that had less ash.

[Edited on 13-1-2015 by maxenzo2]

[Edited on 14-1-2015 by maxenzo2]

Artemus Gordon - 13-1-2015 at 17:40

Just guessing here, but there is an old magic trick where the magician challenges a person to burn a sugar cube with a match or a cigarette lighter. The person can't do it, but then the magician tries it and his sugar cube burns very well. The trick is that cigarette ash is secretly rubbed on a small area of the cube. The ash catalyzes the burning of the sugar. So maybe your charcoal ash catalyzed the sugar burning without consuming all the KNO3 and this caused the remaining nitrate to decompose to something that smells of ammonia?

maxenzo2 - 13-1-2015 at 18:08

Quote: Originally posted by Artemus Gordon

Just guessing here, but there is an old magic trick where the magician challenges a person to burn a sugar cube with a match or a cigarette lighter. The person can't do it, but then the magician tries it and his sugar cube burns very well. The trick is that cigarette ash is secretly rubbed on a small area of the cube. The ash catalyzes the burning of the sugar. So maybe your charcoal ash catalyzed the sugar burning without consuming all the KNO3 and this caused the remaining nitrate to decompose to something that smells of ammonia?

yeah i have think about it also,but the thing is,the smell of ammonia only showed up when i messed the bottom close to the metal plate,not on top were i started digging,thats why its so strange,maybe it created some amine that smells like ammonia? i have no idea,i wont be making the experiment to try it because of the gas that smelled like ammonia,it can be some very toxic stuff and not ammonia and has its smell.

deltaH - 13-1-2015 at 21:04

I also think the ash was catalytic is some kind of way, but the other mystery is what was the nitrogen source. It would be interesting to confirm that indeed the nitrate was reduced to ammonia, okay, it's the opposite of what most would consider the prize... but nevertheless very interesting

maxenzo2 - 13-1-2015 at 21:46

Quote: Originally posted by deltaH

I also think the ash was catalytic is some kind of way, but the other mystery is what was the nitrogen source. It would be interesting to confirm that indeed the nitrate was reduced to ammonia, okay, it's the opposite of what most would consider the prize... but nevertheless very interesting

i have found this ammonia reduction ,if its possible to reduce nitrate to ammonia its possible something like that happend,one thing is for sure i have no idea how it happend lol it wasnt my intent to do it at all.

Molecular Manipulations - 13-1-2015 at 21:55

Quote: Originally posted by deltaH

I also think the ash was catalytic is some kind of way, but the other mystery is what was the nitrogen source.

Why catalytic? It could easily have been a reactant, see my first post.
Also, how is the nitrogen source a mystery? There's nitrogen in potassium nitrate.

macckone - 13-1-2015 at 22:17

Oxalic acid could be formed by nitric acid oxidation of sucrose.
Oxalic acid is a well known reducing agent.
Metal and oxalic acid will produce hydrogen.
The potential mechanism is still open but an efficient
Mechanism for producing ammonia from potassium
Nitrate would be interesting.

deltaH - 13-1-2015 at 22:22

@Molecular Manipulations

I would have liked to see additional confirmation by way of experimentation that it was indeed a nitrate reduction, that's all I meant, but it does look to be very unlikely that it has come from anywhere else.

As for your original equation

3 H2CO + KNO3 + K2CO3* 2 H2O → 3 CO2 + NH4 + 3 H2O + 1.5 K2O

does not make sense. It is unbalanced in carbon and NH4 is incorrect and furthermore, the carbonate decomposition to CO2 and K2O is a separate reaction that you can pulled out of this equation, i.e. it need not be necessary for the reaction H2CO + KNO3 →..., plus I wouldn't say that the potassium here ultimately ends up as K2O, that requires quite high temperatures that I don't think this reaction reaches (especially if it is fuel rich). I'd say the formation of K2CO3 is more likely.

Furthermore, I'd caution against a stoichiometric equation because this type of reaction may well not be stoichiometric. If reducing conditions prevail, then the carbon may well land up as some mixture of carbon black, CO and CO2, depending on the temperature.

[Edited on 14-1-2015 by deltaH]

Molecular Manipulations - 13-1-2015 at 22:50

You're right, I was tired and didn't quite ballance the equation, also meant NH₃ of course.
The potassium carbonate was put in to raise the pH, because it works with aluminum. Also it added hydrogen, from the hydrate it contains, which may have been unnecessarily.
How about this?

2 KNO₃ + 4 H₂CO → 2 NH₃ + K₂CO₃ + 3 CO₂ + H₂O.

Potassium carbonate on each side canceled each other out, but may have been present to allow the reaction to happen. So in this sense you're right about it being a catalyst.
Yes a stoichiometric equation surely didn't happen, but there's no point in writing a non-stoichiometric equation.

deltaH - 14-1-2015 at 00:08

No worries at all and this looks much better/plausable. Base catalysis may be an important factor... also adding something like unslaked lime to sink all the CO2 generated as carbonate may be useful to force more ammonia production... maybe.

Something like fusing a mix of sugar, KNO3 and unslaked lime targeting the hypothetical equation:

2 KNO3 + 4 H2CO + 4CaO→ 2 NH3 + 2KOH + 4 CaCO3

Might even produce anhydrous ammonia

This would certainly ensure basic conditions!!!

It would probably be difficult to ignite and there is the danger of making some CO gas, not to mention the extreme irritation of producing noxious ammonia gas in copious amounts... if this work.

[Edited on 14-1-2015 by deltaH]

maxenzo2 - 14-1-2015 at 03:21

Quote: Originally posted by Molecular Manipulations

You're right, I was tired and didn't quite ballance the equation, also meant NH₃ of course.
The potassium carbonate was put in to raise the pH, because it works with aluminum. Also it added hydrogen, from the hydrate it contains, which may have been unnecessarily.
How about this?

2 KNO₃ + 4 H₂CO → 2 NH₃ + K₂CO₃ + 3 CO₂ + H₂O.

i confirm the metal plate is ferrous not aluminium,its a bit rusted with red iron oxide,but not that rusted so probably its an alloy of some kind.

macckone - 14-1-2015 at 11:02

Aluminum is generally not used for plates in BBQ pits, it melts.

deltaH - 19-1-2015 at 10:13

According to the wiki on zinc nitrate... adding zinc metal to conc. nitric acid reduces it to ammonium nitrate along with producing zinc nitrate, of course. So the reduction of nitrate to ammonia has a simple precedence that I was not aware of.

[Edited on 19-1-2015 by deltaH]

Molecular Manipulations - 19-1-2015 at 10:53

Interesting.
I forgot to mention, a few days ago I tried this using stoichoimetric sucrose and potassium nitrate with about 10% added potassium carbonate. I think I smelled a little ammonia, but if so it wasn't very much. I then tried the same but with cellulose instead of sucrose, the ammonia smell was much stronger, indicating cellulose can reduce nitrate better.
I also tried varying ratios of both carbonate and nitrate, with both cellulose and sucrose the most ammonia was produced from a very slight excess of nitrate (relative oxidation requirements of the fuel) and less than 15% carbonate but more than 5%.
Of course this is only rough approximations as the only indicator for ammonia is smell.

[Edited on 19-1-2015 by Molecular Manipulations]

AJKOER - 23-1-2015 at 14:50

Quote: Originally posted by Molecular Manipulations

Interesting.
I forgot to mention, a few days ago I tried this using stoichoimetric sucrose and potassium nitrate with about 10% added potassium carbonate. I think I smelled a little ammonia, but if so it wasn't very much. I then tried the same but with cellulose instead of sucrose, the ammonia smell was much stronger, indicating cellulose can reduce nitrate better.
I also tried varying ratios of both carbonate and nitrate, with both cellulose and sucrose the most ammonia was produced from a very slight excess of nitrate (relative oxidation requirements of the fuel) and less than 15% carbonate but more than 5%.
Of course this is only rough approximations as the only indicator for ammonia is smell.

[Edited on 19-1-2015 by Molecular Manipulations]

The K2CO3 and moisture/steam can behave very basic. In this regard, it behaves similarly to aqueous Na2CO3, which on boiling will dissolve Aluminum, releases Hydrogen and forms Sodium aluminate (which is why one cannot place aluminumware in a dish washer). Now, per this source, "Journal of the Society of Chemical Industry", Volume 27, page 484, link http://books.google.com/books?pg=PA484&lpg=PA484&dq=... to quote:

"3. Reduction by nonmetals.—The well-known detonation of charcoal and nitre leads to the formation of a carbonate and only small quantities of nitrite. When brought under control by the addition of caustic soda and lime the reaction between sodium nitrate and graphite patented as a process for preparing sodium nitrite (Grossman, Eng. Pat. 1452 of 1904; and also Knop, Eng. Pat. 4747 of I897)."

So, under alkali conditions elemental Carbon (produced from heated sugar along with H2O and other products) may reduce KNO3 to KNO2.

Further, as I have previously noted with Aluminum at elevated pH to quote:

Quote: Originally posted by AJKOER

For those wishing to work with more friendly metals and readily available to turn nitrates into nitrites, consider Aluminum (Al foil no less). Per one source (see equation [1] under Section 6.4, link:
https://docs.google.com/viewer?a=v&q=cache:Jz8OCxPNXSoJ:...), to quote:

"1. 3NO3- + 2Al + 3H2O → 3NO-2 + 2Al(OH)3

2. NO-2 + 2Al + 3H2O → NH3 + 2Al(OH)3 + OH-

3. 2NO-2 + 2Al + 4H2O → N2 + 2Al(OH)3 +2OH-

Nitrate reduction was found to be pH dependant. At pH values less than eight
no nitrate reduction took place. Above pH 10.5 nitrate was reduced upon addition of
the aluminium powder. Aluminium powder has been suggested for the denitrification
of sodium-based nuclear wastes, employing the nitrate to ammonia and ceramic
(NAC) process (Mattus et al., 1993, 1994)."
.........

So, I suspect also with added Carbon, similar to the Aluminum reaction, possibly a quasi selective reduction to ammonia could be obtained.

Speculatively, Hydrogen may also be participating in the reduction of the nitrite if it is formed by the attack of the hot aqueous K2CO3 on the metal alloy in the grill, however, the action of H2, in the modern literature, is usually associated with some form of porous metal catalyst (see, for example, "Catalytic reduction of nitrate and nitrite ions by hydrogen: investigation of the reaction mechanism over Pd and Pd–Cu catalysts" by O.M.Ilinitcha, L.V.Nosovaa, et. al., available at https://www.google.com/url?sa=t&source=web&rct=j&... ).

If one is incline to trust some dated literature, where the actual reaction pathway may not accurately be identified, interestingly the Hydrogen route is tauted. To quote, for example, from page 570 at https://books.google.com/books?pg=PA570&lpg=PA570&dq...

"6. The reduction of nitrates to ammonia by nascent hydrogen and the recovery of the ammonia produced by distillation and collection in standard acid."

and, also, on relative merits, quoting from the same page:

"Where nitrates are present in considerable quantities the reduction method with nascent hydrogen is to be preferred over all others."

But, if the so called nascent hydrogen is created by the action of Al (or Zn) on NaOH (or possibly KOH, in the current context), the actual pathway for NH3 formation is more likely the electrochemical one detailed above, that is, the Aluminum alloy (or Carbon based?) pathway in which, the burning sugar is only providing water vapor . As galvanic cell reactions are more persistent in nature (especially at low concentrations where this 1906 book also ostensibly recommends it), the dated literature recommendation is, in my opinion, more actually congruous with such an electrochemical pathway, as is a mixed metal (especially Aluminum alloy) grill.

[Edited on 24-1-2015 by AJKOER]

m1tanker78 - 23-1-2015 at 17:10

I might have misunderstood your experimental setup (accidental or otherwise); Could it be that the sugar/nitrate mix did little or nothing except to heat the unburnt charcoal and produce 'foam'. Activated charcoal (lump wood charcoal in this case) can adsorb quite a bit of ammonia as well as other molecules. When heated, the same are driven from the charcoal. I've observed a smell of ammonia when dry-distilling ground up lump charcoal. I also collected a fraction of alcohol and other light organic liquid from that experiment. Yet another fraction smelled very strongly like acetic acid. Obviously, the ammonia didn't condense but I could easily detect it coming from the vac takeoff barb of the apparatus. It was a little bizarre and unexpected but can recall it being short-lived.

Based on that, it could be that the 'foam' allowed the ammonia gas to collect instead of diffusing and/or decomposing as usual in the intense heat of burning charcoal. Wood ashes in a steel pan usually produce a musty, weak ammonia-like odor when water is added. I'm not sure what that's all about and never really cared enough to investigate further. I don't think it's ammonia though.

IF a reaction DID occur to produce ammonia, maybe the ashes provided a large surface area to promote intimate mixing of the reactants?? Depending on the conditions, the sugar may have turned into high surface area carbon and facilitated such a reaction. It's hard to speculate and even harder to reproduce such an experiment.

Out of curiosity, what type of charcoal was it? Mesquite, oak, ... what brand?? The charcoal I used was mesquite with a crystal appearance (the kind that 'tings' when you tap it). This charcoal is made by burning mesquite in a big hole in the ground then quenching with dirt before it's consumed. It's then dug up and processed/bagged and sold regionally.