Sciencemadness Discussion Board

check for urea in ammonium nitrate

DocX - 8-6-2022 at 21:32

So I have some supposed ammonium nitrate collected a long time ago from cold packs. In the ingredients list it said "ammonium nitrate", and I got a bunch of them.

Recently I made some tannerite for a friend by mixing a portion of the pellets with aluminum powder. Packed it up good to make an explosive target for target practice at the shooting range. However, it didn't work.

I now wonder if all or parts of my supposed ammonium nitrate stock might actually be urea. I have a nice big jar full of these pellets. and I wonder: is there a way to analyse it to see if urea is present?
The molecules are so much alike I can't really figure out how this could be done.

B(a)P - 8-6-2022 at 22:14

As you seem to be ok with handling/manufacturing explosives.
Dissolve a small sample in a little water. Add some concentrated nitric acid.
If you get a white precipitate that will likely be urea nitrate and this will confirm the presence of urea.
If you want to know how much of your ammonium nitrate/urea is actually urea, then weigh out your sample and weigh the precipitate once dried.

DocX - 9-6-2022 at 07:53

I'm not EXTREMELY comfortable with explosives, no. But tannerite is reasonably indolent, and nor I or anyone else will be anywhere near it when it's subjected to enough energy to react. It is after all sold in gas stations in various parts of the US.

But thank you! Great tip! It can be tried with minuscule amounts, so safety is ok. I'll report back as soon as I get the time to actually do it.

The next quest, if I can confirm urea contamination, is of course to separate the two. But that's another thread.

[Edited on 20222222/6/9 by DocX]

PirateDocBrown - 10-6-2022 at 09:25

Mix with kerosene. Light with a fuse, from a safe distance. There is a large difference in the resulting reaction.

DocX - 11-6-2022 at 23:08

Large difference depending on what? Like I said, this is probably a MIX of urea and ammonium nitrate. So there's nothing to compare with.

Deathunter88 - 12-6-2022 at 02:07

Quote: Originally posted by DocX  
Large difference depending on what? Like I said, this is probably a MIX of urea and ammonium nitrate. So there's nothing to compare with.


There will be no difference. Nothing will happen in either case. You need a blasting cap, a good booster charge, and a critical diameter to initiate ANFO.

PirateDocBrown - 12-6-2022 at 06:22

Quote: Originally posted by Deathunter88  
Quote: Originally posted by DocX  
Large difference depending on what? Like I said, this is probably a MIX of urea and ammonium nitrate. So there's nothing to compare with.


There will be no difference. Nothing will happen in either case. You need a blasting cap, a good booster charge, and a critical diameter to initiate ANFO.


It won't detonate, but it will burn.

Arthur Dent - 12-6-2022 at 06:59

Thank you B(a)P for the tip.

So if I understand, nitric acid will produce a white precipitate in the presence of urea, but will remain clear if it's pure Ammonium Nitrate?

I also have several cool packs that have little information on their composition. I'll test them out right now. :)

Thanks!!!
Quote: Originally posted by B(a)P  
As you seem to be ok with handling/manufacturing explosives.
Dissolve a small sample in a little water. Add some concentrated nitric acid.
If you get a white precipitate that will likely be urea nitrate and this will confirm the presence of urea.
If you want to know how much of your ammonium nitrate/urea is actually urea, then weigh out your sample and weigh the precipitate once dried.

B(a)P - 12-6-2022 at 14:05

Yes that is correct. And if you weigh your sample, every gram of urea will give you about two grams of urea nitrate. You will then be able to work out the percentage of your sample that is urea.

[Edited on 12-6-2022 by B(a)P]