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Author: Subject: Nitric Acid and Silver Nitrate
digga
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A useful link for relating the percentage of Nitric Acid by weight from density and temperature:

http://www.handymath.com/cgi-bin/nitrictble2.cgi?submit=Entr...
Fulmen
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I'm trying to make a bit of silver nitrate and have run into some odd behavior. The nitric acid was made from dilute H2SO4 (appr 10%) and an excess of Ca(NO3)2, added in portions until no more CaSO4 precipitated. But when I add the 925 silver I get more white ppt. I filtered off the ppt and added more Ca(NO3)2, no reaction. Added the silver again, and again I get more precipitate. What's happening?

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fusso
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 Quote: Originally posted by Fulmen I'm trying to make a bit of silver nitrate and have run into some odd behavior. The nitric acid was made from dilute H2SO4 (appr 10%) and an excess of Ca(NO3)2, added in portions until no more CaSO4 precipitated. But when I add the 925 silver I get more white ppt. I filtered off the ppt and added more Ca(NO3)2, no reaction. Added the silver again, and again I get more precipitate. What's happening?
Is both H2SO4 and CN pure?

Fulmen
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Battery acid and recrystallized fertilizer grade. So, not really but it shouldn't be THAT bad. The second/third batch of precipitate did discolor in sunlight, but this disappeared after a wash with NH3.

We're not banging rocks together here. We know how to put a man back together.
Fulmen
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I have to assume it's coming from the silver alloy somehow. Although the amount has subsided there is still some precipitate forming. It's a light, white, almost waxy suspension that collects at the top layer. The main alloying component seems to be copper (blue-green tint that turns blue with ammonia), but there could be other elements there as well.

We're not banging rocks together here. We know how to put a man back together.
Sulaiman
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Sorry to make this thread even longer but I could not resist the temptation

I have a small batch of silver nitrate crystalising from nitric acid at the moment that has quite nice crystals growing that I want to show off

Scale: The liquid is 15mm deep

The large-looking crystal centre-left is only a fraction of a millimetre thick,
it has grown to look like like a feather.

During the writing of this the feathery crystal has 'melted' a little
presumably due to the heat of the led torch illuminating from below.

This batch is I think the third re-crystalisation of the same silver nitrate over a few years,
the original Ag surce was a 99.9% Silver Eagle,
I've been trying to eliminate the 0.1%

My current level of understanding is that photo-sensitivity is most commonly caused by organic contaminants,
so I'm going for purity and 'cleanliness'.
The 100ml beaker has a 90mm dia. filter paper covering it, sealed to the wall with tape.
This keeps out dust and slows down the evaporation rate.

CAUTION : Hobby Chemist, not Professional or even Amateur
j_sum1
22-12-2018 at 13:31
j_sum1
1-1-2019 at 12:56
clearly_not_atara
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silver pyroglutamate and succinimide

There continues to be no easily accessible alternative to nitric acid for the dissolution of silver. Oxamate is tedious to prepare and isolate; lactate is too easily oxidized; sulfamate is rather disappointing; trifluoroacetate is not available; fluoride is dangerous; and alkanesulfonates require a multi-step preparation via the alkyl halides.

Silver pyroglutamate, C5H6NO3Ag, forms white crystals which melt at 176-180, and are slowly colored by exposure to light; it is soluble in dilute alcohol and in boiling water, but only sparingly soluble in cold water.

Amides are generally resistant to oxidation, but may be attacked by halogens. Pyroglutamate is sold as the magnesium salt or by itself as a dietary supplement, or it may be prepared in good yield by heating glutamic acid to 180.

Silver pyroglutamate is also oxidized to succinimide by persulfate, but this depends on persulfate oxidizing Ag+ to Ag2+, which then undergoes a Hunsdiecker-like reaction. In fact, the oxidation is catalytic in silver and provides excellent yields of succinimide from glutamate by aqueous reaction, making it one of the better methods available for the preparation of succinimide:

https://pubs.rsc.org/en/Content/ArticleLanding/2014/RA/C4RA0...

[Edited on 04-20-1969 by clearly_not_atara]
halogenstruck1
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you can buy silver nitrate AgNO3 at any amount from
www.givanchemi.com 30$for 25g and 58$ for 50g

he sells to individuals and not only companies.

he sends from Canada to all countries and good quality. he also sells on Ebay with givan-chem profile. I bought and quality was perfect as also mentioned on ebay reviews for his sales.

[Edited on 25-4-2019 by halogenstruck1]
Herr Haber
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After heating my reactor to get rid of most HNO3 (excess silver) I extracted part of the solution to drop out the silver.

So I got a big mass of silver nitrate. It was very tempting to filter it...

The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
morganbw
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 Quote: Originally posted by Herr Haber After heating my reactor to get rid of most HNO3 (excess silver) I extracted part of the solution to drop out the silver. Somehow in the process I slightly forgot about this thing called a solubility curve So I got a big mass of silver nitrate. It was very tempting to filter it...

Just a touch of what I consider beautiful, thank you sir.
YoctoByte
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I have some silver plated flatware from which I want to remove the silver metal. Using nitric acid works perfectly but I need a lot of it since it also dissolves most of the base metal.

Nitric acid in high concentrations is not available where I live so I have to make it myself which takes a lot of time. Instead, I want to use ammonium nitrate which is more easily available for me;

Ag + 2 NH4NO3 -> [Ag(NH3)2]NO3 + NO2 + H2O

Some catalytic nitric acid or maybe even sulfuric acid (is diamminesilver(I) sulfate soluble?) is needed to get the reaction going.

The diamminesilver(I) complex is stable under basic conditions (see Tollens' reagent) but is it also stable under acidic conditions? If it is not than the acid would be neutralised during the reaction;

[Ag(NH3)2]NO3 + 2 HNO3 -> AgNO3 + 2 NH4NO3

I would try this right now if I could but I'm not at home this week..
Herr Haber
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For plated silver HNO3 is very very wasteful.

You're better off with electrolysis and scraping / flaking as much of the silver as possible. Then you can process the mess at the bottom of your cell in the way you want.

The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
clearly_not_atara
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 Quote: Originally posted by YoctoByte I would try this right now if I could but I'm not at home this week..

I would hope you don't try it at all, it might not work or it might make a loud noise and get broken glass everywhere.

[Edited on 04-20-1969 by clearly_not_atara]
YoctoByte
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Thanks! I'll try electrolysis then.

Another method I just thought of is to dissolve most of the silver layer with nitric acid until some of the base metal is exposed. In my experience about 70-80 percent of the silver is recoverable this way. And then dissolve the base metal in hydrochloric or sulfuric acid to collect the remaining silver. These acids are a lot easier to buy than nitric acid.

To answer my previous question (Is the diamminesilver complex stable under acidic conditions) source (woelen.homescience.net):
 Quote: "Never allow alkaline solutions of silver (I) compounds with ammonia to stand for more than one hour. If there is some silver waste in the form of such solutions, add excess acid to them, in order to neutralize the ammonia. With ammonium ion, such complexes are not formed."

So I guess ammonium nitrate is useless.

 Quote: Originally posted by clearly_not_atara I would hope you don't try it at all, it might not work or it might make a loud noise and get broken glass everywhere.

I would immediately add copper scrap to reduce the silver ions back to silver metal after the silver is dissolved. That way there is no time to form explosive silver compounds, right?
clearly_not_atara
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My suggestion would just be to cut the silverware in half, dissolve the whole mess in hydrochloric acid and filter off the unreacted silver.

Do not attempt to use ammonium nitrate to corrode transition metals, period. Concentrated solutions of ammonium nitrate can explode, and transition metals catalyze the reaction. See:
https://pubs.acs.org/doi/pdf/10.1021/ja01040a011

There's just no good reason for there to be a risk of explosion here. There are plenty of non-blowy-uppy ways of doing this.

[Edited on 04-20-1969 by clearly_not_atara]
Herr Haber
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 Quote: Originally posted by clearly_not_atara My suggestion would just be to cut the silverware in half, dissolve the whole mess in hydrochloric acid and filter off the unreacted silver.

I tried that.
Lots of HCL & big volumes of waste for very little silver in the end.

The truth is that most cases the silver layer is so thin you'll get mud with silver in it. Rarely will you be able to scrape off shards of silver.

In any case, I dont recommend dissolving all the base metals.
You just have to admit it'll be a wasteful process and decide if you can let go of a little silver or use lots of acid and time to separate everything.

I have 8 or 9 kilograms of plated crap in a box. I'll have to get rid of it someday in one of those gold & silver places because there's simply no way I'll be processing this. Too messy.

The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
YoctoByte
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Coincidentally I found an interesting procedure for selectively removing silver plate in a book about electroplating this week.

Add 19 parts by volume concentrated sulfuric acid to 1 part 68% nitric acid and heat up to 80 °C. Then add the silver plated objects. The silver is removed within minutes and the copper alloy base metal is not attacked at all. When the nitric acid is almost depleted you can add some more.
The solution becomes slightly yellow/green and the produced silver salt almost completely dissolves. Some traces of white powder (probably silver sulfate) still coat the base metal so you can wash the metal objects in a beak of water. Then add sodium chloride to the water collect the silver chloride.
By far the most silver seems to collect in the sulfuric acid though. You can precipitate this by adding some hydrochloric acid DROPWISE! (I wouldn't want to use NaCl because that contaminates the acid with sodium ions). A violent reaction happens and hydrogen chloride gas is evolved and a white precipitate is formed (AgCl). The sulfuric acid is very viscous so wait at least a day to let the silver chloride sink to the bottom. The sulfuric acid is decanted and is still a bit cloudy and could probably be used for a next run. The silver chloride at the bottom is washed with water and collected.

This procedure is probably only useful if you have concentrated sulfuric acid to spare and a lot of silver to process but hopefully someone finds it useful!
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 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Nitric Acid and Silver Nitrate Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum