TLutman
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NH₃
I’m about as noob as it gets, trying to not make things that easily can get out of hand until I get a better grasp on this new hobby.
Recently I synthesized NH₃ from urea from DEF and NaOH drain cleaner using nurdrages video as a guide. While not getting the yield he acquired, I
still managed just shy of 20gr NH₃ in 100ml H₂O. I believe I can get a better yield, and think I know where I can pick it up at, so I’m
thinking I will run it again in the near future to find out. Also need to figure out the difference in precipitates I got. I started in a 100ml
erlenmeyer flash and ran it for several hours. I let it cool, and got 17gr. I corked off the flasksfor the night and went back to run it a bit longer
the next night. The precipitate turned to concrete in the bottom, so I decanted to a smaller flask to run it longer. That’s where I picked up
another 3gr, and I turned off the heat when I started to get some bumping,with the solution turning noticeably more viscous. Upon cooling, the
precipitate stayed a very free flowing fine powder in the solution. The same temp/ stir speed was used. Any thoughts?
This might be a noobie question ( I am), with absolutely zero chem classes, but regarding the solution i have . Is it particularly useful in that
concentration, or would I be better off trying to boost the yield, trying to hit a particular yield?
I have no particular project in mind for this, only to build a reagent stock while trying to learn.
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j_sum1
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I made some NH3 a week ago.
Chilling the receiver is critical. Also having a long tall vessel (measuring cylinder) helps with absorption. Going slow helps too.
I got ~90% yield from my reagents and concentration of 22%. The latter figure was low because I just used too much water. I added ice to my receiver
without measuring it. The 90% is not a worry. Reagents are cheap and I simply stopped when it became slow.
Method used was dry NaOH and (NH4)2SO4 with excess NaOH. Heat as well as water from addition funnel were both applied when the gas evolution slowed.
I have never tried urea. I have heard mixed reports on the usefulness of ammonium sulfate versus urea with different people having a favoured reagent
and complaining of foaming issues with one or the other.
20% certainly is useful. 25%+ is obviously a bit better but you shold be able to do most of what you want with the lower concentration. Have some
fun making copper complexes or dissolving some cotton in schwiezer's reagent.
J.
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TLutman
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The urea / NaOH never foamed a bit. Vapors burned the cuts/ abrasions I always seem to have, and being ammonia, stinks horribly when not in the hood ,
but nothing exciting happened. I might try the ammonia sulfate method in the future as well, since I have a big bag of it. As for the cooling, I had a
250ml Erlenmeyer flask in a 500ml beaker filled with ice water. That lasted a little while, but not long enough. I’m looking at making a peltier
cooler for such times, as well for doing recrystallizations. Just not sure how it will handle being on a stir plate.
I have to revisit a few synthesis that didn’t work out, as my scale was wildly inaccurate with anything over 1g before I look at new projects. Yes,
I replaced the scale with a new one. Still trying to keep it simple for the moment.
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B(a)P
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Nice work TLutman, that is definitely a useful concentration.
I have just been making some NH3 today. I used a similar procedure to you. I placed 90 g urea (fertilizer grade) and 120 g of NaOH (drain opener) in
200 mL DH2O in a flask. The flask was fitted with a vacuum take off adaptor with the top stoppered and the vacuum port attached to rubber tubing, the
end of which was attached to a glass tube inserted into the receiver.
The urea/NaOH solution was then gently heated and stirred for four hours.
For my receiver I used a 100 mL measuring cylinder containing 50 mL of water inside a high walled 1 L beaker containing a NaCl ice slurry, which was
changed out twice during the procedure. At the top of the receiver I placed a cotton wool plug to reduce the rate at which any undissolved NH3 escaped
and keep the concentration of NH3 above the water in the receiver high.
My concentration of ammonia based on a density measurement was about 30% by weight.
I haven’t calculated the yield, I am sure it is terrible, but I was after high concentration not yield and the reagents are cheap for me.
Definitely agree with j_sum1, go slow and keep your receiving vessel well chilled.
Have fun!
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Fyndium
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I made a liter of NH3 by this way. I made it in two phases, first a test run and then I concentrated the solution with second run and I got about 35%
(SG 0.88) and I accidentally breathed in just a little whiff of it when I was changing the stopper and it burned the * out of my nose. I only cooled
it with tap cold water. It has been in a bottle, stable as it is for few months now, and I'm not sure where I'm gonna use it.
It is a very viable way to generate ammonia.
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TLutman
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I originally tried on a small scale using a Pyrex washing bottle. It didn’t appear to have enough pressure to come through the glass frit, and the
yield was not very good. I would get spurts of bubbling as the solution heated, then nothing to speak of. I had thoughts of hooking vac to it with an
adjustable bleed valve to control the flow, but think I’m also trying to make things overly complicated. Still, I might try it as proof of concept
for myself.
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