[Tryptamine]

Hey guys, I've got another general chemistry question for you, and I'm hoping that it's not to difficult.

Anyway, in Chemistry class (102) my chemistry teacher gave us an extra credit assignment to figure out how to get the purest form of ammonium nitrate. (NH₄NO₃) He gave us some clues but none that really helped me much.

So I was doing some research, and discovered that the preferred nitrogen source of fertilizers was ammonium nitrate. But I have no idea how I would go about extracting the pure(est) form of it, or if it's even possible to extract it from a the fertilizer.

The second thing that came to my mind was simply the base ammonia. With further investigation I found that to get ammonium nitrate from ammonia, the solution would have to undergo a "protonation" reaction. (Adding an H+ which most of you probably already know) Now I wasn't sure if this reaction was possible in a normal house-hold environment or if a lab would be needed. Would this also be the only reaction needed from "house-hold" ammonia? (ammonium hydroxide)

I don't actually have to bring in pure Ammonium Nitrate, just give a detailed description of how to obtain it.

So to summarize my question(s) up, 1. How would I extract NH₄NO₃ from a fertilizer and 2. How would I go about making it from the solution Ammonia.

Thank you all for your advice!

-Robert

[Arkcon]

Your second plan, protonation of household ammonia, is seriously flawed.  So read more before you submit that one.

Now, as for purifying commercial fertilizer, you'll have to look up what's in it, and how the impurities differ from ammonium nitrate, before you talk about what purification method you've chosen.

[AWK]

Commercial fertilizer (ammonium salpetre, ammonium nitrate) is a qute pure compounds made from ammonia and nitric acid. It contains only minor addition to prevent caking.
Crystallization (with eventual decolorization with active charcoal - this should be done with cold solution for goodness sake) is sufficient.

[Tryptamine]

Thank you for your help so far, luckily for me this isn't due until next week..

Anyway, I found that fertilizer has 3 numbers on the container, each corresponding to the "Primary Nutrients." N-P-K (Nitrogen, Phosphorus and Potassium)

You can buy fertilizers that only have 1 of the Nutrients, and the one containing the most Ammonium-Nitrate has the numbers 33.5-0-0. Unfortunately I'm unable to find any online that show this ratio and I haven't had time to run to the store yet. I'm not even sure Walmart will have fertilizer(s) during the winter..

Does anyone know of a brand of fertilizer that has the 33.5-0-0 ratio?

Here's a link to ratio/nutrients: http://aggie-horticulture.tamu.edu/GREENHOUSE/NURSERY/GUIDES/green/sources.html

Would it be easier to extract the ammonium Nitrate from liquid fertilizer or solid?

Also, what chemical reaction would I need to perform on the fertilizer to get the NH₄NO₃?

Thanks for your help once again!

-Robert

[Arkcon]

The N-P-K numbers are a fertilizer convention for percentages of elements that plants need in fairly large amounts.  These numbers aren't what you're looking for as a chemist seeking raw materials.  What you want is an ingredients list. 

The "N" in fertilizer can come from a variety of sources -- potassium nitrate (provides some "K"), calcium nitrate (plants need Ca for strong cell walls), or even urea.  They can be converted to ammonium nitrate (the first two easier than the last one,) but that's a roundabout way of addressing your need for ammonium nitrate.

Let's see some ingredient lists, and look up their individual properties andd see what you can do to get ammonium nitrate.

[Kryolith]

Sounds very suspicious to me... Why do you need a fertilizer brand/source if it is just a theoritical work? Why should one try to extract an explosive from fertilizer and not order it legally? What's the learn effect of such a "homework"?

@Tryptamine btw.: Nice username 

[Tryptamine]

Kryolith,

A specific type/brand of fertilizer is imperative in the theoretical question because if I just stated that you could obtain Ammonium Nitrate from fertilizer, then that could imply many different types, (Animal Feces, Solid/Liquid plant food, etc.) and would undoubtedly result in a lower score on the paper. Not everyone in my class is going to take the same route that I did, and choose fertilizer as their base for the extraction process. From the research that I've done, I personally decided that fertilizer would be the best medium to extract the Ammonium Nitrate from.

My professor and I both know that you can legally buy it, but doing so would completely defeat the purpose of the question. This is somewhat of a "Think Outside the Box" question, therefore being an extra credit assignment.

I apologize if my questions come across as "suspicious", but I assure you that I am simply a kid in college, fascinated with chemistry and working hard to get an excellent score in the class.

Hope that clears things up for you. If you have any more questions just ask.

And thank you for the compliment on my username 

[Kryolith]

Hmm ok. Just a thought 

Can you use chemicals from your school?

50-60% nitric acid + ammonia works fine. Furthermore it's a lot easier than the extraction of any fertilizer.

Your second plan, protonation of household ammonia, is seriously flawed.

? ? ?

[Arkcon]

Not everyone in my class is going to take the same route that I did, and choose fertilizer as their base for the extraction process.

Actually, I'm pretty sure there's going to be a lot of uniformity in the papers.  There's only one way to manufacture it industrially, and there's only pretty much only two uses -- nitrogen source in fertilizer and oxidixer for explosive mixtures.

Returning to the purification, what have you learned recently about purifying methods?

[Tryptamine]

Kryolith - Unfortunately, no. I'm not actually creating the Ammonium Nitrate anyway, so asking the professor for some nitric acid wouldn't work. The only thing I can think of is if I synthesized nitric acid and then added it to the ammonia.. but I think that would require more work than extracting it from a fertilizer.

Arkcon - I didn't know that their wasn't many uses for it (I'm still a new chemist) so that kinda sucks. I wanted to have an original, unique paper.

Also, we haven't really covered purification methods yet, that's coming up in the next chapter. Maybe that is why he gave this as an extra-credit assignment... to prepare us for the next chapter.

Would you mind covering some basic ones?

Thanks again,

-Robert

[Arkcon]

AWK already gave you one - recrystallization.  If the fertilizer is a mixture of ammonium nitrate, superphosphate (that's fertilizer jargon for Ca(H₂PO₄)₂₎) and trace metals (usually as chelates,) recrystallization can give you a pure solid.

[Tryptamine]

Recrystallization looks like the method I think I'm going to write my paper on. After searching the web and various chemistry books, it appears to be the best way.

Hypothetical Method: If I were to saturate fertilizer grade ammonium nitrate in methanol, the impurities would precipitate and I could then strain the methanol into another container and allow it to cool. As I let it cool down, crystals would begin to form and they would be the purest form of NH₄NO₃ that I could get.

Does that sound like a legit explanation? I will go into much further detail when I write the actual paper, but I wanted to hear you guys' opinions on the extraction process.

Quick question - Would NH₄NO₃ be soluble in Ethanol since it's soluble in Methanol?

Thanks again,

-Robert

[Arkcon]

I don't have a legitimate reference in front of me right now that says what ammonium nitrate is soluble in, which is OK, you will have to reference your source when you write the paper, so if you see it in print, you're golden.

You will have to be sure any and all impurities are are complete insoluble in water/ethanol/methanol/whatever to say that recrystilization is a good purification method. 

If that's not the case, you'll have to do fractional crystallization, an important beginner purification method in college classes, which I'd suspect is where you teacher is going with this assignment.

Either that or here's a latent pyro.

[EDIT]

The wikipedia article on recrystallization is a pretty good one -- clear diagrams, covers all topics, check it out.

http://en.wikipedia.org/wiki/Recrystallization

[Tryptamine]

Excellent article on crystallization Arkcon, Thank you. I also found an article on Ammonium Nitrate:

http://en.wikipedia.org/wiki/Ammonium_nitrate

I'm not sure if I am aloud to use Wikipedia as a reference since anyone can edit the content of the online dictionary, but I will ask my professor when I see him next.

In the wiki article about NH₄NO₃, it states that the salt is highly water-soluble, if this is true, instead of using methanol/ethanol for a solvent could water possibly be used?

Actually I don't think water would work since the boiling point of water is 212^oF and the boiling point of Ammonium Nitrate is 375.8^oF.

I read off another website that it was soluble in methanol, but I'm not sure how reliable that website is. So I'll do some further research there.

IF it actually is soluble in alcohol, then could I saturate the fertilizer with it, and then heat the mixture? I know from a previous lab we conducted that solubility increases when the temperature increases (also stated in the Wikipedia article), but how hot would I need to make the mixture?

I'm sure my professor knows the boiling points of both, so I don't want to heat it up to the point where it becomes unstable/combustible, that would result in a flawed technique and definitely get some points marked off.

Once again, thank you all for your help, I've learned alot through just one assignment!

[Arkcon]

Excellent article on crystallization Arkcon, Thank you. I also found an article on Ammonium Nitrate:

http://en.wikipedia.org/wiki/Ammonium_nitrate

I'm not sure if I am aloud to use Wikipedia as a reference since anyone can edit the content of the online dictionary, but I will ask my professor when I see him next.

I wouldn't if I were teaching.  Use the reference in the wikipedia page, if there is one, and if you can find it to check.  Otherwise, it's over to the library for you ...

In the wiki article about NH₄NO₃, it states that the salt is highly water-soluble, if this is true, instead of using methanol/ethanol for a solvent could water possibly be used?

You won't need another solvent besides water, but that wikipedia page provides a reason why you might want to.

Actually I don't think water would work since the boiling point of water is 212^oF and the boiling point of Ammonium Nitrate is 375.8^oF.

OK Tryptamine, you have officially left the building with this statement.

I read off another website that it was soluble in methanol, but I'm not sure how reliable that website is. So I'll do some further research there.

IF it actually is soluble in alcohol, then could I saturate the fertilizer with it, and then heat the mixture? I know from a previous lab we conducted that solubility increases when the temperature increases (also stated in the Wikipedia article), but how hot would I need to make the mixture?

I'm sure my professor knows the boiling points of both, so I don't want to heat it up to the point where it becomes unstable/combustible, that would result in a flawed technique and definitely get some points marked off.

Once again, thank you all for your help, I've learned alot through just one assignment!

Please don't use the words "heat" and "ammonium nitrate" so casually.  I like talking to you on these forums, and you'll need a least a few fingers for that.