[xchcui]

Hi.
I would like to understand what happens exactly when i make electro cleaning to a copper oxide object.i browsed a lot in the web and i didn't find appropriate explanation.
I make a solution of vinegar+some salt.
I connect the copper oxide object to the negative voltage(as a cathode)and  a copper wire to the positive voltage(as an anode).
I understand that in the solution there are hydrogen,oxygen,chlorine,soduim and copper ions,ch3oo- and h2o.
When i close the circuit i understand that hydrogen bubbles create around the copper object,oxygen bubbles create around the copper wire(maybe also chlorine)and the object get rid of the oxygen atom during the process.
What is actually happens?:
Does the anode-wire dissolved and get eaten in that process?does it release copper ions?
Does the copper oxide object(cathode),besides than get rid of the oxygen,also plated with a kind of material,maybe with the copper that might dissolved from the anode wire?
Does the oxygen ion release from the copper oxide object,even,before i close the circuit?
I will be very appreciate to hear an expert explanation what is happening exactly in that process.
Thanks in advance.

[Arkcon]

I think what you're doing is called electropolishing, basically the reverse of electroplating -- you make the piece you want to polish the cathode, essentially using it to plate the anodes.  This removes the underlying metal, and cleans the piece.  See a fuller description here:  http://en.wikipedia.org/wiki/Electropolishing

[xchcui]

Hi Arkon.
thanks for your link.
I read the link but it is not exactly my case.
In my case the object is connected to the negative voltage and not to the positive while i make electro-cleaning in order to get rid of the oxidation on the object.
I focused my questions on the specific things that i look for an answer which will let me understand few things about the process.

[billnotgatez]

@xchcui
Is there a link that shows the recipe' for your process?

[xchcui]

Hi billnotgatez.
It is very simple electrolyte.
Vinegar 5%+some salt.
Copper object as the cathode
Copper wire as the anode.
What is happening in the solution regarding to my questions?

[billnotgatez]

@xchcui
I am thinking you are electroplating and not electrocleaning or electropolishing
Maybe it is just a matter of semantics.

As the original poster, I had expected you had done some of the Internet research and had a link handy. I had expected you would post it as a courtesy.

By the way, for the ingredient salt are you referring to Sodium chloride?

Also, By the way, I am not an expert, but I am trying to get some background so we might attract an expert to the discussion.

[xchcui]

billnotgatez.
The pinch of salt that i had to the white vinegar 5% is regular salt NaCl.
Before i am going to plate my object by electroplating with different solution,i am going,first,to get rid of the oxide that on the copper object.so i put my object and the wire at the vinegar+salt solution in the way i described before.I know that i get rid of the oxide from the cathode(my object)but i try to found out by an expert chemist what is happening in the solution regarding my pevious questions?

[Borek]

Have you checked if the cleaning doesn't work without potential source as well?

I remember reading that the combination of Cl^- and mild acid dissolves CuO with CuCl (yes, Cu(I)Cl) being an important intermediate. I don't remember details and I am not sure they were in a published paper, they just came from a fellow chemist.

[xchcui]

Using potential source work better to clean the object surface(oxide).
Thanks for trying to help,but i hope there is some one expert that can refer to my questions and explain(describe)all the process that happens in the solution.

[xchcui]

Anyone?
This is very simple solution.
i am not a chemist,so i don't know what is happening in that electro cleaning process even though this is very simple reaction,so i turned to the expert of chemical forum and i am very suprise that nobody can explain the process.This is chemist forum,where are all the chemists

[billnotgatez]

http://chemistry.about.com/cs/demonstrations/a/aa022204a.htm
http://www.youtube.com/watch?v=H4N-iGvYrbM
http://chemistry.stackexchange.com/questions/5863/why-add-salt-to-vinegar-to-clean-pennies
http://www.exploratorium.edu/science_explorer/copper_caper.html
http://wiki.answers.com/Q/Why_do_you_clean_pennies_with_salt_and_vinegar?#slide=1
http://thehappyscientist.com/science-experiment/penny-chemistry-part-1

The above is a FYI for anyone following this thread.

[eazye1334]

You are doing reverse electrocleaning, aka cathodic cleaning, with the setup you have. You are actually plating onto the surface of the part. Your copper wire is dissolving into the solution creating Cu²⁺ ions. Those ions, along with any other loose ions in the solution, will travel through the electrolyte and plate onto your part. Hydrogen is evolved at the part surface, creating a bubbly "scrubbing" action that helps to clean any dirt off. Cathodic cleaning is a good method of preparing surfaces for things like electroplating.

However, this being said, the proper way to complete this is to reverse the current and make the part anodic for a brief period. This reverses the process and actually dissolves some of the working part, essentially what you plated in the first step. Oxygen is liberated at the part surface and the copper ions dissolve back into the solution, taking impurities and metal smuts with them. Finishing this way gives you a much cleaner surface.

I don't know what else you want to know.

[Tittywahah]

At the risk of making you even more frustrated I thought I might chip in.  I do a lot of copper working, and amongst other things I clean sometimes. I can not add anything to eazya description except to say that Oxidation of Cu- takes place at the anode and reduction takes place at the Cathode, there is an electron gain at he cathode and electron loss at the anode.  Having said that, are you actually wanting to clean copper? If so this is not the best method - simply put a tiny amount of Copper sulphate as the electrolyte in de-ionized water and attach impure copper to Anode and the pure piece at the cathode.  I wondered also at your original description: 'Copper Oxide'  to me this is impossible to do, you have oxide layers on top of pure elemental copper, is this what you mean?  Forgive me if I misunderstand anything, but the oxide layer is simply what you are getting rid of and revealing pure copper in the process.
Kind regards

[xchcui]

Hi  eazye1334.

I see that the best method to clean the part is to do it in two steps.one time the part will be the cathode and after that a brief period as the anode.
It seems reasonable,but there are two thing that i try to figure out:
1)When i make the part anodic for a brief period and oxygen is liberated at the part surface.Doesn't the negative oxygen ions(O--)oxidize the part again and make the part surface to be copper oxide again(CuO)?
I know that the O-- ions give electron to the anode and become a gas,but what happens next,that cause the Cu++ ion to drop into the solution,rather than be connected with the oxygen ions in order to form CuO again?
2)When i make the part cathodic and the H+ ions take electrons from the copper oxide surface part and turns to bubbles gas,How does this action cause the oxygen from the part surface to be removed?
Also,when the oxygen is removed from the part surface in that process,the part is also being plated with Cu++ ions and with other loose ions in the solution,Isn't it disturb to the cleaning process?


Tittywahah.
In my orginal description when i said copper oxide,i mean layer of oxidation on the copper surface(CuO)
and in the electro cleaning i wanted to get rid from the oxygen on the surface before electro plate it.
But as you can see i have little problem to understand few thing at this process.

[Tittywahah]

Hi there,
???and in the electro cleaning i wanted to get rid fron the oxygen on the surface before electro plate it.
Are you trying to clean the copper?
And then what do you want to electroplate it with?
I am failing to understand, exactly, what the end result is that you desire, are looking to achieve.