Sciencemadness Discussion Board

Urea Recrystallization

Hexavalent - 9-2-2012 at 11:41

I recently heated up 700g of urea in 100ml of water to recrystallize it . . .but, soon after I smelt a strong odour of ammonia. What was going on here?

UnintentionalChaos - 9-2-2012 at 11:50

Hydrolysis or formation of biuret. Some is probably unavoidable, keeping the temp lower will help, though recovery will not be as good (hey, urea is dirt cheap anyway) I've had success in using alcohol/water mix to reduce the ridiculous solubility of urea in water, prevention the cooled solution from resembling a brick.

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Hexavalent - 9-2-2012 at 11:52

Thanks!!

I picked up 2kg of urea for 99p at a local discount store, sold for ice removal. As soon as I found its solubility data, I knew it was time to reach for the big flasks:)

Is it possible, out of curiosity, that urea could generate hydrazine on its own?

Hexavalent - 9-2-2012 at 11:55

Also, what happens if I accidentally inhale some of the biuret? The MSDS isn't all that helpful. . .

UnintentionalChaos - 9-2-2012 at 11:56

Quote: Originally posted by Hexavalent  
Thanks!!

I picked up 2kg of urea for 99p at a local discount store, sold for ice removal. As soon as I found its solubility data, I knew it was time to reach for the big flasks:)

Is it possible, out of curiosity, that urea could generate hydrazine on its own?


no.

Biuret isn't particularly harmful unless you're a plant. Wikipedia would inform you that it is used as a non-protein nitrogen supplement for animals, if you had bothered to read it.

Also, you see that little button in the top right hand corner of your posts that says "edit?" Use it.

For the multiposts you already made, click edit, check the little box that says "! Delete this message !" and hit edit post.

[Edited on 2-9-12 by UnintentionalChaos]

Magpie - 9-2-2012 at 13:12

see last post, this page:

http://www.sciencemadness.org/talk/viewthread.php?tid=7413#p...

Hexavalent - 9-2-2012 at 14:08

Thankyou UC and Magpie . . .I wasn't aware on how to delete double posts. Like the video on the Grignard reaction BTW UC.