urea not reaction

[Alfred Beit]

I have a nice batch of AR but am getting no reaction from the Urea. Ideas?

 

[nickvc]

Urea is used to neutralise the excess nitric so if you have no reaction it's because you have no excess nitric.

 

[4metals]

If your reaction consumed the nitric so there is no excess, then the urea will not visibly react. What were you digesting? You may have exhausted your acid and dropped the values. Have you tested the liquid with stannous chloride?

 

[Geld Konig]

Are you sure that your "urea" is really urea or is Na NO3 (or saltpeter) ? Try use copper to see reaction with brown color fumes. Or boil the solution a little to see brown fumes.

 

[Anonymous]

Are you sure that your "urea" is really urea or is Na NO3 (or saltpeter) ?

Saltpeter is a nitrate,I am sure he didn't confuse those two.

 

[Alfred Beit]

We are digesting black sand ore and ore without magnetics.

 

[shyknee]

We are digesting black sand ore and ore without magnetics.

stannous anyone?

 

[Harold_V]

Are you sure that your "urea" is really urea or is Na NO3 (or saltpeter) ? Try use copper to see reaction with brown color fumes. Or boil the solution a little to see brown fumes.

You should know better than to advise ANYONE to boil a gold chloride solution (assuming it is one). That is NOT acceptable, not for any reason. If you must dispense advice that relates to evaporation, please use that term instead. All too many take your comments literally. We try to avoid giving misleading information here.

Harold

 

[Joeforbes]

I added some urea to just concentrated Nitric Acid, and there really wasn't much of a reaction. A small amount of fizzing but not much else. I too was puzzled by the fact that urea seemed to have no reaction in my AuCl solution after dissolving gold so I decided to see how the highest case concentration reacted.

 

[butcher]

Small amounts of urea in nitric acid will remove NO2, the fizzing you witnessed, I would think that 68% nitric would just replace the NO2 as HNO2 in solution as quickly as the small amount of urea reacted.

so a few prills of urea in volume of nitric acid has little effect, to me would be like adding few prills of caustic soda to a gallon of H2SO4 yes you had some react but overall not much change to the sulfuric acid.

 

[Joeforbes]

Small amounts of urea in nitric acid will remove NO2, the fizzing you witnessed, I would think that 68% nitric would just replace the NO2 as HNO2 in solution as quickly as the small amount of urea reacted.

so a few prills of urea in volume of nitric acid has little effect, to me would be like adding few prills of caustic soda to a gallon of H2SO4 yes you had some react but overall not much change to the sulfuric acid.

I only used 10ml of nitric acid, and used about half that volume of urea. It was enough that it took a very long time for it to fully dissolve. The resulting nitric had no effect on a penny that I let sit in it overnight.

 

[eeTHr]

If you evaporate the nitric out of your AR, and use proper dilution, you won't need to contaminate your AR with urea.

 

[freechemist]

I have a nice batch of AR but am getting no reaction from the Urea. Ideas?

No wonder, that there is no visible reaction. Urea and nitric acid together form a highly water soluble salt, urea nitrate, which in fact is a very dangerous compond. More information about it you can get in "Wikipedia": http://en.wikipedia.org/wiki/Urea_nitrate or by a google-search using "urea nitrate" as a term to search for. After having read enough stupidities about urea, which may endanger severely anybody believing them and working according to them, here my earnest warning: Do never use urea to "neutralize" nitric acid, - it won't do the job, - and never use urea together with concentrated nitric acid or nitrates in a concentrated acid medium.

freechemist