Σldritch
Hazard to Others
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Registered: 22-3-2016
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The reaction of urea and aluminium
I reacted 100g urea molten and about 10g of aluminium with Cupric Chloride as a catalyst (~500mg max) thinking i would reduce the urea to some
interesting amine. The reaction went quite well with the aluminium dissolving into the urea with the evolution of some gas at around 120 degrees
Celsius. I let it cool and dissolved it in about 300ml of water and left it overnight to dissolve everything thoroughly.
However when i woke up there was no solution but a thick gel of something. What is it?
Some notes:
The gas was probably only partially composed of ammonia since the smell was not terrible even though the reaction was performed indoors. The solution
was neutral at evening and the gel is neutral too. The solution i spilled had grown small fluffy crystals by the morning.
I speculate Aluminium Cyanate was somehow which on standing in aqueous solution hydrolyzed to Aluminium Hydroxide (which formed a gel), urea and
Ammonium Bicarbonate which formed the fluffy crystals by sublimating from the spilled solution. What does not fit with this explanation is where the
ammonia went if mostly hydrogen was produced. The reaction would look something like this i think:
6 CO(NH2)2 + 2 Al = 2 Al(CNO)3 + 3 H2 + 6 NH3
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AJKOER
Radically Dubious
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Registered: 7-5-2011
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The reaction appears to have started with a standard chemical reaction and was followed (an apparent inception period) by electrochemical one. The
action of Al on CuCl2 liberated Copper metal which means you now have the workings of a galvanic cell complete with electrolyte. See relatedly https://arxiv.org/pdf/1611.09951.pdf .
This adds electrons to the mix and apparently also the .H (monoatomic hydrogen radical) which self-reacts (.H + .H = H2 (g)) liberating some hydrogen.
The hydrogen radical will attack the CO(NH2)2.
Not surprising as Al is very electropositive metal, and Mg is even more so, which I recall reacts significantly with urea liberating H2 and NH3 (see
https://books.google.com/books?id=jvjmAAAAMAAJ&pg=RA1-PA... ), which supports your contention as to gaseous products.
[Edited on 18-6-2019 by AJKOER]
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