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Author: Subject: Solubility of copper nitrate in nitric acid?
Twospoons
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[*] posted on 29-12-2010 at 16:45
Solubility of copper nitrate in nitric acid?


Anyone have a figure for this? I've tried and failed to find it with good ol' google.
FYI its part of an experiment separating silver nitrate from copper nitrate. Silver nitrate is relatively insoluble in 68% nitric acid - confirmed when I added more nitric to concentrated copper/silver nitrate soln and got lots of little white crystals.
Yes, its the old 'get the silver out of sterling silver' problem. I've read the other threads about this, and seen the other methods - I want to try something a bit different.




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[*] posted on 29-12-2010 at 18:12


AFAIK those kind of salts are not very soluble on their corresponding acids, that's common-ion effect.

Why dont you try to remove the cupric nitrate by lixiviating it in alcohol? A quick search affords that 1 part of Cu(NO3)2 is soluble in 1 part of alcohol at 12.5 ºC while AgNO3 is only soluble 1 part in 30 of alcohol, so there you go. If you cant afford loosing that silver, then you can leave the solution to it's own device and light will tear silver nitrate in to silver oxide, witch can be filtered.
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[*] posted on 29-12-2010 at 23:41


Copper nitrate is extremely soluble in water IIRC not sure about nitric acid. I don't even believe it is possible to isolate in a crystalline form from an aqueous solution. If you're trying to get the silver (something I've done in the past) just dissolve the sterling in dilute nitric acid, filter to get the silver nitrate solution, precipitate silver with copper metal, filter and melt the silver into a small ingot and purify via electrolysis.



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cyanureeves
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[*] posted on 30-12-2010 at 07:06


that makes sense. you can nitrate the recovered silver again if you want silver nitrate and your copper nitrate will be in solution.
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[*] posted on 30-12-2010 at 14:20


Ok, I've just redissolved the crystals I got from adding nitric acid. There is still some blue colouring - but it is much less intense.
On a side note: I found a quick way of getting clean water - ice from inside our old freezer! Its one of those ones that doesn't auto-defrost so it steadily builds up ice on the inside walls.

I wouldn't go the alcohol route due to the risk of forming silver fulminate.




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[*] posted on 30-12-2010 at 19:13


Okay, a writeup is at hand...

Adjust pH of your solution to something like 6, and dilute to make silver displacement by copper feasible if concentrated (le chatlier).

Watch silver metal forming after adding copper metal and mix until no more silver is formed, filter and wash thoroughly with clean water . Dissolve silver metal in Nitric acid, basify with e.g. NAOH or KOH, add sugar (yes, regular table sugar), heat to 100 degrees Celsius in a beaker with a watchglass on top or similar apparatus under heavy stirring for atleast 24 Hours. Semi coarse grains is produced which apparently has a very high purity, could not produce the article as my PC is down.





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[*] posted on 30-12-2010 at 19:25


Twospoons? Did you just say clean water from a freezer? Im not sure if you have checked it yet but smell anything that has been freezer burned from your freezer, it should assure you that water is anything but clean. It is indeed full of aromatic hydrocarbons and not worth the scaping considering how cheep distilled or spring water is from the store. Condensation from your heater is about as clean as the ice from your freezer.




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[*] posted on 31-12-2010 at 10:34


It was the cleanest I had on hand. Not much is stored in our freezer, and it doesn't smell. Mostly I wanted to avoid chlorine.
I wouldn't trust store bought water to be any cleaner. If I want really clean water I would carbon filter then distill.
Bottled water may be cheap in your part of the world, but it costs more than petrol around here. Stupid really.




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[*] posted on 31-12-2010 at 17:15


I would add HCl to precipitate silver chloride and get copper nitrate/chloride solution.
Then I would convert AgCl to Ag and Cl. Dissolve metallic silver in nitric acid and you have silver nitrate solution.

Then precipitate copper carbonate from the copper nitrate/chloride solution and again mix that copper carbonate with nitric acid.

Solutions should be separated then :D
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[*] posted on 31-12-2010 at 18:35


Quote: Originally posted by Random  
Then I would convert AgCl to Ag and Cl.
WTF?
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[*] posted on 31-12-2010 at 18:38


Quote: Originally posted by entropy51  
Quote: Originally posted by Random  
Then I would convert AgCl to Ag and Cl.
WTF?


On exposure to light it decomposes to silver metal and chlorine.
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[*] posted on 31-12-2010 at 19:36



Quote:

On exposure to light it decomposes to silver metal and chlorine.


ok and then it will be oxidized " after the reduction process " to AgO
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[*] posted on 31-12-2010 at 19:51


Quote: Originally posted by Random  
I would convert AgCl to Ag and Cl


Bad idea. AgCl is annoying it isn't water soluble, it turns into very hard clumps that are nearly impossible to break up. Sunlight and heat only convert the outer layerto silver, and glucose reductions are messy and inefficient.

Stick with the method I mentioned.




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[*] posted on 1-1-2011 at 03:10


S that wont work, but
There is also maybe working method with NaOH:

Put NaOH to silver and copper nitrate solution, it will precipitate AgOH, Ag2O and Cu(OH)2.
Heat that precipitated mixture until silver oxides and hydroxides will decompose to elemental silver and Cu(OH)2 to CuO and water.
Then mix decomposed mixture with hydrochloric acid to dissolve copper oxide. Elemental silver will be left.

sodium carbonate could also be used instead of lye and maybe it is even better option due to small solubility of ag(oh)2

[Edited on 1-1-2011 by Random]
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[*] posted on 1-1-2011 at 08:50
If you can't dazzle them with your brilliance ...


boggle them with a reference.

This from —

Linke's
Solubilities Inorganic and Metal-Organic Compounds
D. Van Nostrand
1958
2 Volumes 1914 pages.



Copper-nirate-800.jpg - 207kB

[Edited on 1-1-2011 by The WiZard is In]
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[*] posted on 1-1-2011 at 13:22


Thanks for that. An answer to the original question!



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[*] posted on 1-1-2011 at 14:12


Twospoons you also stated it was the old silver extraction from sterling.you got about two or three methods for that now.what is copper nitrate in nitric acid for? what is it other than copper nitrate in nitric acid?the add hcl method method will give you silver metal and chloride if you drop zinc in it wont it?i tried that zinc and hydrochloric acid method and watched the silverchloride turn to black silver and eventually grey mud right before my eyes.i always threw away the left over chloride. i guess i could've evaporated it and gotten zinc chloride?
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[*] posted on 1-1-2011 at 14:23


wait a minute, i'm confused now.. don't you still have silver and copper nitrate on your hands?:(
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[*] posted on 1-1-2011 at 16:45


Quote: Originally posted by cyanureeves  
Twospoons you also stated it was the old silver extraction from sterling.you got about two or three methods for that now.what is copper nitrate in nitric acid for? what is it other than copper nitrate in nitric acid?the add hcl method method will give you silver metal and chloride if you drop zinc in it wont it?i tried that zinc and hydrochloric acid method and watched the silverchloride turn to black silver and eventually grey mud right before my eyes.i always threw away the left over chloride. i guess i could've evaporated it and gotten zinc chloride?


Or you can precipitate zinc carbonate from that with baking soda
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[*] posted on 1-1-2011 at 17:13


thank you. i jumped in Twospoons' thread here. o.k. now! when ever i precipitate silver chloride by adding NaCl to sterling digested in nitric acid,i do end up with sodium nitrate, copper nitrate and a bit of chlorides as well in solution don't i? would it be possible to extract the sodium nitrate?but unless i'm dissolving a whole tea pot i guess it would'nt amount to much.
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[*] posted on 1-1-2011 at 21:47


The idea was to displace silver nitrate from the mixed nitrates by adding excess nitric acid. Silver nitrate solubility is ~2g in 1000ml of 68% nitric. Looking at that ref from Wizard, copper nitrate solubilty is 10X that.



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[*] posted on 2-1-2011 at 01:58


Quote: Originally posted by cyanureeves  
thank you. i jumped in Twospoons' thread here. o.k. now! when ever i precipitate silver chloride by adding NaCl to sterling digested in nitric acid,i do end up with sodium nitrate, copper nitrate and a bit of chlorides as well in solution don't i? would it be possible to extract the sodium nitrate?but unless i'm dissolving a whole tea pot i guess it would'nt amount to much.


you will have silver chloride solid and copper/sodium nitrate solution
add some more NaHCO3, Na2CO3 or NaOH to precipitate CuCO3 or Cu(OH)2 and then you have solution of sodium nitrate
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[*] posted on 2-1-2011 at 07:17


great! AgOH and Ag2O? heck i want those now.
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