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Author: Subject: Ammonia Generation
Murexide
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[*] posted on 29-12-2018 at 15:02


Quote: Originally posted by Abromination  
Quote: Originally posted by Murexide  
Ground glass arrived with no problems (I hope)! Setup is pretty much the same as Xeon, except I don’t have a gg stopper for the top addition funnel so I’ll have to substitute with some tape and paper. Saturated ammonium sulfate solution is in the addition funnel to be dropped onto solid hydroxide (I don’t feel comfortable with very concentrated hydroxide solutions). Then heating is commenced after full addition and bubbling ceases.

I’ll work on a 6/10 molar scale based on ammonia (39.6g ammonium sulfate, 27g sodium hydroxide) to dissolve in 50 mL water, so that should produce a max concentration of 12M or 20.4%. In practice, if I get above 14% that is sufficient for my purposes.

Once I try this out soon I’ll report on how the yields with the gg equipment compare.


Very professional, although several notes:
1. Since you do not have a ground glass stopper, if your addition funnel is pressure equalizing, I would suggest putting the hose adapter to the suck back trap on top of the PE funnel and to place the PE funnel directly onto your reaction flask.
2. I would also suggest adding around a 5 percent excess of sodium hydroxide as it is hydroscopic, meaning that when you weigh it out the water weight will slightly throw off your calculations.
3. I would dissolve both your NaOH and ammonium sulfate to allow for a more efficient production of ammonia.

Just the insight of an amateur ;)

[Edited on 28-12-18 by Abromination]


Photos of my attempt are below. Unfortunately, even with the ground glass setup I produced only 2M ammonia. There was a strong scent of ammonia, so I suspect the funnel trap was not very efficient and leaked ammonia (as others wrote). Dripping initially produced very large amounts of ammonia gas, but gas production quickly tapered off as more ammonium sulfate solution was added (expected - more water to dissolve ammonia). The RBF was heated for 90 min and a consistent rate of gas expelled (not sure whether this was ammonia or water vapour). The quick MO Titration was done at the completion of the 90 min. Something I did note was unr3acted hydroxide pellets seemed to be stuck to the bottom. Not sure whether this was because of excess reagent or physical separation.

About the notes, the hose adapter has ground glass joints both on top and bottom, and gas outlet at the side. So if it is placed at the top, the top covering will require covering likewise to the current setup (although a balloon was mentioned - this could be useful to prevent extreme pressure buildups). The hydroxide was already accounted to a 10% excess due to water. I considered dissolving NaOH, but concentrated solutions of hydroxide are extremely hazardous and increasing the water used increases the amount of ammonia dissolved in the reaction flask.

The glass funnel does seem to be the limiting factor here. Replacement with a glass rod and measuring cylinder as someone suggested is the method used by Nile Red and Doug’s Lab seems to be necessary to ensure the bubbles travel for a longer length of water. I will have to use a make shift suck back trap though, perhaps using one of my conicals, lengthen of glass tube and a two holed stopper. I will attempt ammonia production sometime in the future, although currently my ammonia can accept sodium contamination (so I’ve used the pure Chloride And aqueous hydroxide method). But my hydroxide is not pure and may contain impurities that interfere with my purposes, so I will eventually attempt this again.

97992F78-4EE9-4808-A660-665C419E098E.jpeg - 1.3MB 31CC5FD4-1F25-4A7F-AC9C-02A00D4F175A.jpeg - 1.4MB
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draculic acid69
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[*] posted on 30-12-2018 at 04:48


Quote: Originally posted by XeonTheMGPony  
Quote: Originally posted by draculic acid69  
Murexide: another thing I can add is that you will have better luck bubbling formed gas thru a thin tall cylinder rather than a wide flat beaker and just putting the hose into the water rather than the upside down funnel seems to work better for me.doing this rxns in glass also seems dangerous and unnecessary compared to using plastic.ie coke bottles .also using solutions of either chemical and adding all at once will lead to an exothermic reaction followed by dramatic and then catastrophic rise in pressure of a caustic gas.not what you want.using that much water to generate the gas even by dropping it into the flask slowly will also hold onto a lot of ammonia that will require heating to release requireing cooling of the now hot gas your trying to condense.not what you want.

[Edited on 29-12-2018 by draculic acid69]

[Edited on 29-12-2018 by draculic acid69]


This sounds like some serious slum level cookery methodology!

Just use proper equipment and procedure and there is 0 risk, unlike cooks we know how to do it properly and for the most part proper glass wear.



That's a pretty big call for some guy who had shit blow up in his face the day before saying what you just said.plastic gas generators are far superior in this case.dont diss them.
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XeonTheMGPony
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[*] posted on 30-12-2018 at 07:17


You have fun with that.
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S.C. Wack
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[*] posted on 30-12-2018 at 09:38


No one mentions cooling the receiver...is it a given or unimportant? My suggestion is buying glass tubing.




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[*] posted on 30-12-2018 at 13:35


I think cooling and active stirring was mentioned. However, I believe the large disparity is due to the funnel leaking most of the ammonia generator. The joints are self dealing with moist ammonia vapour I think.

I have some supply of glass tubes, so I can make something out of that leading into a measuring cylinder
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[*] posted on 30-12-2018 at 14:13


I see. BTW a very nice little book from 1885 mentions the sulfate, pp. 97-108
https://archive.org/details/aceticacidandvi00unkngoog/page/n...
It does not use NaOH so you may find it totally irrelevant and not understand why I would mention it.





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[*] posted on 30-12-2018 at 14:43


Quote: Originally posted by S.C. Wack  
I see. BTW a very nice little book from 1885 mentions the sulfate, pp. 97-108
https://archive.org/details/aceticacidandvi00unkngoog/page/n...
It does not use NaOH so you may find it totally irrelevant and not understand why I would mention it.



It does mention ammonium sulfate + caustic soda, pp. 99-100.

And it is a very nice little book, indeed.
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[*] posted on 30-12-2018 at 16:06


What about using washing soda/sodium carbonate?


(NH4)2SO4 + Na2CO3 = (NH4)2CO3 + Na2SO4. The ammonium carbonate will decompose releasing NH3 leaving ammonium bicarb which will also decompose giving off NH3 + CO2 + H2O.


(NH4)2SO4 + Na2CO3 = (NH4)2CO3 + Na2SO4

Decomp will happen spontaneously (though slowly) at room temp IIRC, but much faster in hot or boiling water
(NH4)2CO3 → NH4HCO3 + NH3

Since the solution would be hot, the decomp of the bicarb should be very quick b/c decomp starts at 36C
NH4HCO3 → NH3 + H2O + CO2
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[*] posted on 30-12-2018 at 16:46


Quote: Originally posted by RogueRose  
What about using washing soda/sodium carbonate?


(NH4)2SO4 + Na2CO3 = (NH4)2CO3 + Na2SO4. The ammonium carbonate will decompose releasing NH3 leaving ammonium bicarb which will also decompose giving off NH3 + CO2 + H2O.


(NH4)2SO4 + Na2CO3 = (NH4)2CO3 + Na2SO4

Decomp will happen spontaneously (though slowly) at room temp IIRC, but much faster in hot or boiling water
(NH4)2CO3 → NH4HCO3 + NH3

Since the solution would be hot, the decomp of the bicarb should be very quick b/c decomp starts at 36C
NH4HCO3 → NH3 + H2O + CO2


Ammonium carbonate can be very difficult to work with, as it sublimes and condenses in a fashion that is rather difficult to control. It usually clogs something and then blows apart the apparatus (hopefully at a joint).
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draculic acid69
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[*] posted on 30-12-2018 at 20:27


S.C.w.Wack yes cooling is a given obviously.stirring is also a given if available.glass tubing won't make any difference in this case.


[Edited on 31-12-2018 by draculic acid69]
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[*] posted on 30-12-2018 at 20:30


Quote: Originally posted by happyfooddance  
Quote: Originally posted by RogueRose  
What about using washing soda/sodium carbonate?


(NH4)2SO4 + Na2CO3 = (NH4)2CO3 + Na2SO4. The ammonium carbonate will decompose releasing NH3 leaving ammonium bicarb which will also decompose giving off NH3 + CO2 + H2O.


(NH4)2SO4 + Na2CO3 = (NH4)2CO3 + Na2SO4

Decomp will happen spontaneously (though slowly) at room temp IIRC, but much faster in hot or boiling water
(NH4)2CO3 → NH4HCO3 + NH3

Since the solution would be hot, the decomp of the bicarb should be very quick b/c decomp starts at 36C
NH4HCO3 → NH3 + H2O + CO2


Ammonium carbonate can be very difficult to work with, as it sublimes and condenses in a fashion that is rather difficult to control. It usually clogs something and then blows apart the apparatus (hopefully at a joint).


I had a similar result when working with ammonium sulfate but I thought I had been using NaOH, though I might be wrong. I can say I did get a very strong NH3 production but I didn't leave enough headroom in the flask. If you try this I would fill no more than 20% full and not let the bubbled get any higher than about 3/4 from the top of the flask neck head.

I know the gas was clear for the first 20-30 mins until bubbling really started to fill the flask (burbing) pushed some up into the condenser. I was using a 6mm glass tube running from the plugged flask, so not ideal in the least bit, if you have something larger, say 1/2", this might not be such a problem.

Eitherway, the "science" (formula) is sound and I plan to try it again with adequate glass tubing, I'd prefer to run the gas once it exits the 1/2" glass tube into a 3-4ft copper pipe of 3/4" diameter (with a fan or wet rag wrapped around it) to cool the gas before it gets to the water where I wanted it to absorb - and in the case of this thread, reduce the overall energy in the acid reaction.

I know NH3 reacts with copper but I'm wondering if it would carry any of the contaminate into the receiving vessel, I suspect little would pass. I did coat one pipe with a teflon spray (sticks to any metal, plastic and glass) and good for 400F - it works wonders coating brass NPT fittings which corrode with HCl, ammonium sulfate and others, but after spraying with this stuff I've had no corrosion problems. I do coat it 2x and bake dry at 200F for about 15 mins.

The spray is Dupont lubricant spray and it does an awesome job getting stuck nuts and hoses off (hot water hoses to washing machine, completely stuck with a huge -15" pipe wrench, 1 spray and 5 mins later came off with a 6" pipe wrench/pliers)
https://www.amazon.com/DuPont-Teflon-Non-Stick-Dry-Film-Lubricant-x/dp/B018FTA5WA

I got this to coat my soap making molds and I've never had soap stick once even after using the same mold 40-50 times with one coat.

full disclosure - I 'm not sponsored or benefit in any way by the company.
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[*] posted on 31-12-2018 at 10:08


Quote: Originally posted by draculic acid69  
S.C.w.Wack yes cooling is a given obviously.stirring is also a given if available.glass tubing won't make any difference in this case.


The want of gas transfer lines that are inert and don't kink or easily melt, bend, and flex should be unnecessary for me to defend.

It is only recently that I tossed wide mouth Mason jar imitation Woulfe bottles out of my cave, for newfangled Drechsel bottles, yet I feel qualified to attest that here in Crazytown, flexible tubing of all kinds is not particularly inert, especially to hot reactive things.

BTW I note that the first experiment in the first description of bubbling gas into water was in fact NH4Cl/lime ammonia. (1767; Woulfe's familiar improved bottle came in 1784)




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draculic acid69
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[*] posted on 31-12-2018 at 22:19


Crimping and melting can be a problem but can be avoided.bend and flex isn't really an issue in gas lines.dont know much about that brown rubber tubing.probably would be better to have a glass tube instead of that brown rubber stuff.aquarium tube is what I use.
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