# How much urea required for neutralizing 10 litre aquaregia solution?



## decentdude21 (Sep 16, 2022)

I want to neutralize aquaregia with urea. So I want to know how much urea required for neutralize aquaregia?


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## Yggdrasil (Sep 16, 2022)

First an foremost, what you want is to destroy the surplus nitric.
Not neutralize which means bring it to a pH of 7.
Next is that Urea is not a good solution to do it.
Its an excellent fertilizer but not so good for the job you have at hand.
Best would be to not use too much nitric in the first hand.
Secondly if that is not possible, use Sulfamic acid in hot solution.
Or evaporate to syrup and add HCl.

Now why are you asking this same question once more???
We have answered you several times.

Study the replies you have already received and study Hokes book in detail.
You seem to need it.


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## orvi (Sep 16, 2022)

decentdude21 said:


> I want to neutralize aquaregia with urea. So I want to know how much urea required for neutralize aquaregia?


Very general question, very general answer - enough to neutralize the excess nitric  We cannot answer this question, because we do not know how much excess nitric is in there.

As Ygdrassil pointed out, *and it is discussed here regularly like every week - urea isn´t very good nitric destroying reagent*, despite you see it been used in nearly every YT video. Urea does not kill nitric acid, only nitrous compounds like nitrous acid or nitrosyl chloride. Nitric acid form a salt with urea. So fizzing you observe after adding urea isn´t nitric destroyed, but N(III) remains destroyed to elemental nitrogen. 

Abandon urea for de-NOx-ing, and obtain sulfamic acid instead. Heat the solution to 85-90°C and add in small portions to observe the reaction - it could be very violent from the start. You can easily source sulfamic acid as grout remover, or as cleaning agent for coffee machines scale. And it is also purchasable online, and also in bulk as it is quite common chemical. For few euros/kg. Not restricted chemical in most places in the world. Added benefit of dropping lead from the solution as byproduct of nitric decomposition using sulfamic acid is sulfuric acid 

Urea cause formation of very toxic compounds in solution like N-chloroureas, chloramines, nitrogen trichloride (sensitive explosive). In addition, it is very inconvenient to have urea at waste treatment stage since upon addition of hydroxide it liberates ammonia as it slowly decompose.


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## Yggdrasil (Sep 16, 2022)

orvi said:


> Very general question, very general answer - enough to neutralize the excess nitric  We cannot answer this question, because we do not know how much excess nitric is in there.
> 
> As Ygdrassil pointed out, *and it is discussed here regularly like every week - urea isn´t very good nitric destroying reagent*, despite you see it been used in nearly every YT video. Urea does not kill nitric acid, only nitrous compounds like nitrous acid or nitrosyl chloride. Nitric acid form a salt with urea. So fizzing you observe after adding urea isn´t nitric destroyed, but N(III) remains destroyed to elemental nitrogen.
> 
> ...


He has asked the same before, and it has been answered in detail before.


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## Yggdrasil (Sep 16, 2022)

decentdude21 said:


> I want to neutralize aquaregia with urea. So I want to know how much urea required for neutralize aquaregia?


decentdude21, do you read the replies you get, or are you just posting in hope of a different reply?


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## VK3NHL (Sep 16, 2022)

decentdude21 said:


> I want to neutralize aquaregia with urea. So I want to know how much urea required for neutralize aquaregia?


You Do Not ‘Neutralise’ Aqua-Regia with Urea. (Stop)


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## decentdude21 (Sep 16, 2022)

Ok thanks to all for your replies.


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## BlackLabel (Sep 17, 2022)

The answers didn't match the expectations yet… 
Maybe, he's got a ton of urea at home, already ordered and waiting to be used.


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## Jpenzo (Sep 17, 2022)

Probably not the proper thread to ask this question but I'm going to toss it out here anyway. With sulfamic acid, what is the sign that you have neutralized all of the nitric?


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## Shark (Sep 17, 2022)

The reaction becomes less reactive as the nitric decomposes.

Simply put, the fizzing and foaming becomes less as it destroys the nitric acid.


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## Jpenzo (Sep 17, 2022)

Thank you sir! Much appreciated.


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## Harshana552 (Sep 26, 2022)

can we use NaHCO3 instead


orvi said:


> Very general question, very general answer - enough to neutralize the excess nitric  We cannot answer this question, because we do not know how much excess nitric is in there.
> 
> As Ygdrassil pointed out, *and it is discussed here regularly like every week - urea isn´t very good nitric destroying reagent*, despite you see it been used in nearly every YT video. Urea does not kill nitric acid, only nitrous compounds like nitrous acid or nitrosyl chloride. Nitric acid form a salt with urea. So fizzing you observe after adding urea isn´t nitric destroyed, but N(III) remains destroyed to elemental nitrogen.
> 
> ...


can we use NaHCO3 instead


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## Yggdrasil (Sep 26, 2022)

Harshana552 said:


> can we use NaHCO3 instead
> 
> can we use NaHCO3 instead


Welcome in.

Sodium bicarbonate can be used to a lot of things.
But it is impossible for any to answer your question until we know what you wish to do.


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## orvi (Sep 26, 2022)

Harshana552 said:


> can we use NaHCO3 instead
> 
> can we use NaHCO3 instead


No.


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## kurtak (Sep 26, 2022)

Harshana552 said:


> can we use NaHCO3 instead


As Orvi said - the answer is -------

*NO !!! *

Bases - like carbonates or hydroxides target BOTH the nitric AND the HCl in the AR by changing/adjusting the Ph of BOTH acids

If you have free (excess) nitric in your AR you DO NOT want to change the Ph of both acids --- rather you want to "drive off" - "get rid of" - just the free/excess nitric - this is called de-NOxing the AR

You actually "drive" the NOx (or NO2) out of the solution - NOT neutralize the acid (adjust Ph)

You can do that by -------

1) heating the solution which will drive off the excess NOx (not as easy as it sounds)

2) or dissolve metal (gold - or - if done right copper) until all the free/excess nitric in the AR is used up (my preferred method)

3) or use sulfamic acid (not sulfuric acid) as suggested by many/most members of this forum

Here is how sulfamic acid works to "drive off" the excess nitric ------

HNO3 + H3NSO3 → H2SO4 + N2O + H2O

Kurt


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## Maniacop (Oct 8, 2022)

So, How much Urea do I need to neutralize the Nitric acid in my Aqua Regia? (This was an attempt at trying to put a smile on some faces! I have read all threads and just thought it should be asked one more time!!) Have a great day everyone!! Be safe and stay Healthy!!

Brett


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## FrugalRefiner (Oct 8, 2022)

None. 

There's your smile.

Dave


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## eaglekeeper (Oct 8, 2022)

Urea and nitric acid under the right situation can make an unstable compound. I doubt you can make it by accident, but you never know.


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## galenrog (Oct 8, 2022)

Yes, it can be made by accident. My previous neighbor responded to a mystery explosion that turned out to be an amateur refiner that got his information from YouTube. That was many years ago, but he still remembers the smell of explosive residue and burning flesh. 

That is probably why he is training officer for a different department now.

Time for more coffee.


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## FrugalRefiner (Oct 8, 2022)

galenrog said:


> That was many years ago, but he still remembers the smell of explosive residue and burning flesh.


I once saw a car accident happen in right in front of me. Big flames. Several of us pulled the driver of the embroiled corvette out of his car. I will never forget that smell. Gas, fiberglass, flesh. Very bad, but he lived. Tried to bury that memory more than 40 years ago, but when I read your post, it came right back.

Dave


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## eaglekeeper (Oct 8, 2022)

It's amazing they used that compound as a herbicide or pesticide (can't remember which) way back in the day. I would Wikipedia it, but I don't want to be put on a list.


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## Maniacop (Oct 8, 2022)

I hope you all do know that what I last posted was an attempt at a joke.

But on a serious note, say I have Aqua Regia with both Silver and Gold in solution. Sulfamic acid has driven out what little if any Nitric remained. PH is @ 1, Stannous test shows definite gold in solution and from doing the process when the gold was enquarted, the gold was alloyed with silver to get below 6K Gold. After filtering that batch, stannous determined that there was gold in solution and yellow cake at the bottom of the beaker, so it was saved. Mixed a new batch of Sodium Nitrate, Hydrochloric and distilled water for the cake. When trying to precipitate the gold from the first batch, should I drop the silver first? or what should I do to reclaim the 52+ grams of pure AG from solution and still retain whatever amount of gold went into solution.

Thanks a million!

Brett


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## butcher (Oct 8, 2022)

You will not have gold and silver together dissolved in the same solution to any extent. One could be soluble and the other insoluble in a solution, but not both as soluble ions to any extent.

Silver can be dissolved in a solution of nitric acid, gold will not dissolve in nitric acid. Silver is normally parted from gold using nitric acid.

Gold will dissolve in the poor man's aqua regia. silver will not be soluble to any extent in a chloride solution, it will normally be a fluffy insoluble white powder.


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## Maniacop (Oct 9, 2022)

butcher said:


> You will not have gold and silver together dissolved in the same solution to any extent. One could be soluble and the other insoluble in a solution, but not both as soluble ions to any extent.
> 
> Silver can be dissolved in a solution of nitric acid, gold will not dissolve in nitric acid. Silver is normally parted from gold using nitric acid.
> 
> Gold will dissolve in the poor man's aqua regia. silver will not be soluble to any extent in a chloride solution, it will normally be a fluffy insoluble white powder.


The one area that I had a concern, was when I dissolved the alloyed gold to make that cake. I used pure silver (52 Grams) as an alloy. When the beaker settled and cooled, I tested for gold in solution (Knowing that the Nitric dissolved all of the silver) and the stannous showed a positive result? False positive?


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## butcher (Oct 9, 2022)

When you say "Knowing that the Nitric dissolved all of the silver)" this sounds like you parted the gold with nitric acid before dissolving the gold in the poor man's solution, but then again it also sounds in your description as though you dissolve the alloy of both gold and silver in your poor man's aqua regia. 

How are you making cakes from a gold alloy? do you bake these cakes?

Without knowing what you have done in your experiment, it is hard to answer a question about the problem you are having with the experiment.


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## kurtak (Oct 9, 2022)

*Nitric acid alone will not dissolve gold !!!*



Maniacop said:


> (Knowing that the Nitric dissolved all of the silver) and the stannous showed a positive result? *False positive?*


Per the bold print (false positive) this is likely what you are seeing

If you are trying to stannous test a *nitric only* solution that has silver dissolved in it this is what happens

Stannous is made with HCl - so when you add the stannous/HCl to the silver nitrate the HCl creates silver chloride

Silver chloride is very sensitive to light - so when the AgCl (created by the stannous/HCl) is exposed to light it does what is called photo graying

In other words - when exposed to light - the normally white AgCl will change to a purple/gray/black color

So the purple/gray/black photo graying of the AgCl gives you a false positive test for gold because photo grayed AgCl is in the same color range of a positive stannous test for gold

Therefore - *you know* that a stannous test *on silver nitrate* is a false positive because nitric acid (alone) *does not dissolve gold*

Kurt


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