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Author: Subject: Copper Nitrate
Chemgineer
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[*] posted on 24-8-2021 at 16:42
Copper Nitrate


So I produced some copper nitrate by reacting copper pipe with nitric acid, I then used an oven to dry the product to a solid. After grinding it into a powder I tried to ignite some powdered sugar with it. I got a slight fizzing and some worm formations but nothing spectacular.

Is this normal for copper nitrate or does my sample still contain allot of water and this is damping down the reaction?

[Edited on 25-8-2021 by Chemgineer]
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violet sin
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[*] posted on 24-8-2021 at 19:25


If I recall correctly, aqueous made copper nitrate, cannot be dehydrated to anhydrous salt by heating without extensive decomposition to oxide or still having hydration. Wet nitrate performs poorly, dry oxide performs poorly, at oxidizing sugar. There should be a LOT of conversations on here about getting anhydrous copper nitrate.

If I'm wrong, I'm sure I'll be swiftly reminded by the smarter amongst us. And if that's the case my apologies for sowing disinformation.
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woelen
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[*] posted on 25-8-2021 at 00:42


Violet sin is right, heating hydrated copper nitrate leads to decomposition, with loss of HNO3 and formation of a mixed oxide/nitrate. Stronger heating leads to complete decomposition with loss of NO2 and O2 and then only CuO remains.

Making anhydrous Cu(NO3)2 has eluded chemists until fairly recently. Not before the 1960's a method was found for making the anhydrous salt. This requires dissolving copper metal in a solution of NO2/N2O4 in a suitable solvent (I don't remember which non-reactive solvent was used). This then leads to solvated copper nitrate. This solvated copper nitrate then can be heated carefully to drive off the solvent and leaving copper(II) nitrate behind. The anhydrous compound is a covalent somewhat volatile compound, which is very reactive and not commercially available. It is an expensive lab curiousity.




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DraconicAcid
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[*] posted on 25-8-2021 at 08:05


The solvent woelen is thinking of was ethyl acetate.



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unionised
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[*] posted on 25-8-2021 at 09:24


Quote: Originally posted by DraconicAcid  
The solvent woelen is thinking of was ethyl acetate.

...which is "brave".
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DraconicAcid
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[*] posted on 25-8-2021 at 10:45


Quote: Originally posted by unionised  
Quote: Originally posted by DraconicAcid  
The solvent woelen is thinking of was ethyl acetate.

...which is "brave".


Safer than ether......




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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Chemgineer
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[*] posted on 29-8-2021 at 06:34


I just spotted there is a video by NurdRage where he specifically heats copper nitrate to produce nitric acid! I sure did choose the wrong salt to try and dry out!
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Chemgineer
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[*] posted on 9-9-2021 at 02:09


I've taken my partially decomposed sample of copper nitrate, I dissolved it in ethanol as that is what I had to hand. I've then filtered off the oxide which wasn't soluble in ethanol and I have a clear blue solution again. I note that any kind of heating produces more green oxide but if I leave it in an open beaker the ethanol is gradually evaporating. I plan to leave it for an extended period out of curiosity and see if anything crystallises out of solution that is not green.
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[*] posted on 9-9-2021 at 02:27


Quote: Originally posted by Chemgineer  
... in an open beaker the ethanol is gradually evaporating.
If you seal the beaker with a sheet of filter paper
the ethanol will evaporate away a little more slowly
but I think that moisture would be fairly well excluded due to the slightly raised internal pressure.




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macckone
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[*] posted on 9-9-2021 at 11:19


put two beakers in a plastic bag, one with anhydrous calcium chloride and one with your ethanol mix.
The calcium chloride will absorb any water and ethanol.
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Tsjerk
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[*] posted on 9-9-2021 at 13:48


Quote: Originally posted by Sulaiman  
Quote: Originally posted by Chemgineer  
... in an open beaker the ethanol is gradually evaporating.
If you seal the beaker with a sheet of filter paper
the ethanol will evaporate away a little more slowly
but I think that moisture would be fairly well excluded due to the slightly raised internal pressure.


This will unfortunately not work, water inside and outside will be in equilibrium because there is enough time to reach it. There will be a pressure of ethanol inside the beaker concentration wise, but this won't exclude water from the outside. If there is absolute ethanol vapour inside it will even attract water as it is hygroscopic.
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[*] posted on 19-9-2021 at 01:08


copper sulfate and calcium nitrate works but its at about 60*C you will get nitric acid from it, it will decompose in solution giving you copper oxynitrate i believe, turqouise colored insoluble compound sometimes used in pyrotechnics as a weak oxidizer / colorant

i really wonder what properties of anhydrous copper nitrate tetraammine would be like, the hydrated form showed quite high brisance, blowing a clean hole in 3mm steel with just 16 grammes in a glass bottle




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https://en.wikipedia.org/wiki/Solubility_table
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