How does electroplating work at the atomic scale?

  • Thread starter frenchman
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  • #1
frenchman
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Hi, I am trying to understand how electroplating works.
With help of this wikipedia diagramm (http://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Copper_electroplating.svg/471px-Copper_electroplating.svg.png) I have already figured out (correct me if I am wrong) that it works something like this: the electrons from the battery go to the cathode (metal), and reduce the cu2+ in the solution, and electrons are take from the anode (Cu) thus oxydizing Cu(s) in Cu2+ ions.
Wikipedia states " Cu2+ associates with the anion SO42- in the solution to form copper sulfate"
What I don't understand is the following:
-Under what form do the two assiciate? is it still some kind of an ion, even though the association is neutral?
-how does that association travel from the anode to the cathode? Is it just heat that makes the ions move in the solution, and when one of them bumps into the cathode the cu2+ is reduced, or is there some kind of force which attracts the ions to the cathode?
And finally, related to that last question I have a few more:
-what would happen in a solution where the temperature would be reduced near absolute zero?
-what would happen in a solution where the numbers of ions would be reduced to a few in the entire solution?
-what is the role of tension in all this? How do variations of tension translate physically in terms of moving cu2+ ions and of reduction and oxydation?
Thanks in advance for any help
frenchman
 

Answers and Replies

  • #2
Borek
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Generally speaking counterion doesn't matter. Cu2+ gets into the solution on anode and travels as Cu2+ to cathode.

Long before you get close to absolute zero solution solidifies, and the electrolysis slows down to a crawl.
 
  • #3
frenchman
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ok but for the question about how ions move from one side to another, is there any force that help them get to the cathode, or is it only heat that makes them move from anode to cathode? Do the ions move in the solution forming some kind of a beam which goes from the anode to the cathode which would be caused by the attraction of the positively charged ions to the negatively charged cathode or are they randomly distributed in the solution?
 
Last edited:
  • #4
Borek
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Three basic sources of the transport - solution mixing, diffusion and drift due to the electric field. In typical applications drift can be safely ignored, and in the presence of mixing diffusion doesn't matter much as well.
 
  • #5
frenchman
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ok thanks
 

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