# Copper Nitrate Solidified While Cementing Silver



## Arguro_Testudo (Mar 29, 2021)

Good morning everyone. 

I dissolved 500 grams of silver plated copper braid from industrial RG142 cabling into 1.2L of nitric acid and 500mL of distilled water. Not knowing exactly what the silver content is, I made a spreadsheet in attempt to make an accurate guess. The solution completely dissolved the braid without excess nitric, confirmed by putting a few small pieces of sterling silver into the solution while still on the heat and no subsequent reaction was observed. The braid is entirely clean and only consists of Ag and Cu metal.

I then let the solution cool down to about 85-90 degrees F and hastily added some clean stripped solid copper wire to let the silver cement over night. Unfortunately I could not stir the solution overnight, underestimating the importance of the stirring, and when I inspected the reaction this morning, I discovered that the copper wires were stuck in place and that the solution had 'solidified'. The 'solidified' copper nitrate looks like bright blue rock candy and I don't know how to dissolve it so that it can be filtered. There appears to be some silver at the bottom, but the solution was now almost entirely solid copper nitrate. Once I stirred it up, it seemed to go back to a liquid, so I pulled the copper wires out and stirred it more vigorously.

Should I heat this solution or add more distilled water or both? I can try to cement the silver out again, but it appears that I had too much copper dissolved in too little solution and I'm not sure how to rectify the situation. I'm a newbie at this process, but I did my initial test with this braid using 250 g dissolved in 800mL of nitric acid and 1L of distilled water; which was a little bit too much solution but it did not solidify like this. 

Thank you for any help or advice that can be given, once this process is standardized, it should be pretty straightforward. I had just never seen the copper nitrate solidify like this in any tutorial.


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## FrugalRefiner (Mar 29, 2021)

Just add distilled water. No need for heat.

Dave


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## Arguro_Testudo (Mar 29, 2021)

Thank you for this, I will add some distilled water and try cementing out the silver again.

It was certainly a humbling experience to discover the copper nitrate crystal this morning when I was riding high yesterday thinking I had nailed the correct amount of nitric acid to dissolve the braid.

I'll try using a little more distilled water for the next run to avoid the excess copper nitrate.


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## FrugalRefiner (Mar 29, 2021)

Most use a mixture of equal parts nitric acid and distilled water.

Dave


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## Arguro_Testudo (Mar 30, 2021)

I will definitely try that the next run.

I have skimmed off the liquid solution and added water to the copper nitrate crystals, which helped to some degree but some of it is incredibly stuck on the bottom of the beaker. 

I added the liquid solution to a separate beaker and the silver cemented out on pure copper just as it should.

Now I need to figure out how to get these copper nitrate crystals back into solution when they are hardened onto the bottom of the initial beaker. I've been scraping at them with a screw driver but I'm afraid to break the glass beaker. I may try adding some hot distilled water.

Thank you for your help, I was able to get back on track and learned something in the process. The nice thing about this process is nothing is really 'lost' that can't be 'recovered' somehow.


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## kurtak (Mar 30, 2021)

D-water - warm/hot will work better then room temp - heat the water then add to beaker with the copper nitrate crystal - heating the water in the beaker with the crystals (still stuck to bottom of beaker) could cause the beaker to crack &/or brake

stirring the water from time to time will also help

Copper nitrate crystals are "much" harder/dense then silver nitrate crystal so take "much" more time to dissolve then silver nitrate crystals - so as long as you have enough water to actually dissolve the crystals it is just a matter of time

once the crystals dissolve enough that they loosen from the bottom of the beaker & the water is able to get "under" the crystals you can then put it on a hot plate to "warm it" 

Bottom line - all you need is D-water & time with some stirring from time to time & they will dissolve

Kurt


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