I see that urine initially has urea, which has two NH2 groups, and that these turn into ammonia. I have a student who is thinking of making a urine analog with cleaning ammonia. How would she do that? Is there a “normal” concentration of ammonia? Does the ammonia evaporate away quickly if it’s left in the open?
No, there is no ammonia in fresh urine. There may be some in old urine, but it will evaporate quickly. Kitty litter will smell like ammonia after a while. I think you need urea and salt to make an analogue.
WarmNPrickly: not exactly true. The human body does secrete ammonia but in minute amounts relative to urea (IIRC something on the order of less than 1%). But to the OP: what the hell are you trying to make synthetic urine for?
OK, I was going to let this die, as I see that urea is what I really wanted, but a science fair kid is going to try to replicate something of the results mentioned in this article: http://www.greencarreports.com/blog/1022028_can-urine-rescue-hydrogen-powered-cars using 9-volt batteries and different electrode metals. Apparently I misremembered the key chemical as ammonia instead of urea.
My recollection is that urea was the first “organic” compound synthesized from “inorganic” (by some definitions) compounds (ammonia and carbon dioxide, I believe). Apparently this was a big deal; people had this notion that there was a divide between the organic and inorganic worlds.