a p problem

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ettran

Well-known member
Joined
Jan 1, 2014
Messages
89
hi , started a a p process on some gold pins and after a few weeks the liquid turned aqua blue,and there is some white on the bottom. need clues , ed.
 
The blue is a good indication of some copper in the solution, the solution is probably dilute with water and not very acidic.

Other types copper salts dissolved in solution can also give similar blue colors such as sulfates, nitrates, amines ... but that does not seem the case here as we should only be dealing with chloride ions in or out of solution ...

You can add a little HCl hydrochloric acid and oxygen or air to rejuvenate the solution to dissolve the white copper powder (insoluble cuprous chloride CuCl salts) back into solution as a brown saturated both CuCl and cuCl2 soluton or a green CuCl2 solution (higher oxidation state of copper ions )hungry for more copper atoms to dissolve into solution (note adding H2O2 could put you at risk of dissolving any insoluble gold powders into solution).

CuCl2 a green solution (Cupric chloride a higher oxidation state) will dissolve more copper into solution forming CuCl brown (cuprous chloride of a lower oxidation state) as the copper saturates the solution with cuprous chloride it will begin to precipitate this copper salt as a white powder during this process the green cupric solution turns brown as it becomes saturated with cuprous ions as the solution can only hold so much copper because of many factors saturation acidity dilution temperature and so-on, the cuprous chloride will begin to fall out of solution as a white salt or powder of copper insoluble cupreous chloride as the solution is oversaturate with copper (the dark brown solution , the CuCl2 saturated with CuCl) has a hard time of dissolving more copper unless the temperature or some other factor is altered so the solution can hold more copper ions...

(adding water to a white precipitant powder of cuprous chloride CuCl can dissolve some of the copper ions in solution giving a very dilute solution with some copper in solution giving a blue color similar to what your describing.

Cupric chloride CuCl2 will range green to dark brown depending on how much cupric copper ions (CuCl2) or cuprous copper chloride ions CuCl are in solution, the green cupric solution as it dissolves more copper into solution becomes more saturated with copper and the solution darkens to a dark brown to almost blackish as the cuprous ions CuCl ions saturate the solution, as the darker solution cannot hold the the amount of copper ions and only a certain amount will stay soluble the copper salt which will begin to form a white insoluble cuprous chloride powder (once solution is saturated with these copper ions) CuCl white powder can be turned back into CuCl2 green solution with a little acid and air or oxygen rejuvenating the solution to dissolve more copper into solution...

White chloride powders or salts can come from other metals, like silver or lead, with a simple processing you can separate, and or determine what metal salt they are composed of by their solubility's, a simple study can help you understand more...

Do some research to be able to understand the leach and the process and how it works...
Understanding the tool is a first step to understanding how to use it.
 
thank you for your input , you are very kind to me , so if i add more acid it should clear up to clear green ? thank you for this info , ed.
 
Well, it may or it may not. Use this as a test. Take a small sample or your solution in a test tube and try it. Then let us know what the results are. Sometimes, you just have to take things one step at a time. Actually, that's usually the best practice. Take things one step at a time. If things don't go as you expect, that's the time to put the breaks on and try to figure things out before jumping a few steps ahead.

Dave
 
ettran said:
thank you for your input , you are very kind to me , so if i add more acid it should clear up to clear green ? thank you for this info , ed.

The white stuff is possible CuCl and that will turn into a dark brown solution when you add HCl. If you separate the dark solution from the pins and add air via a bubbler or just let it stand for a week or two then the oxygen from the air combined with the HCl will turn it into a CuCl2 solution that is emerald green. Given that your white stuff really is CuCl.

White stuff could also be tin that has oxidized and hydrated, HCl will not dissolve this.

As long as you have exposed copper metal in the same vessel it can be hard to transform enough CuCl to CuCl2 to see the emerald green color.

Göran
 
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