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Need help with electrolysis

  1. Feb 23, 2004 #1

    ShawnD

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    I'm trying to put a copper layer on a piece of steel.
    Here is the equipment I'm using:
    -12v car battery charger
    -bucket
    -water
    -sodium hypochlorite
    -copper pipe
    -piece of steel


    I filled a bucket with water and added a bit of sodium hypochlorite (bleach). The hypochlorite is there to help oxidize the copper to get copper ions. I put curled copper pipe in the solution then connect it to the positive terminal on the battery charger. Then I put the piece of steel in the solution and connect the negative terminal.

    Here is what should happen:
    -the bleach will be forced to reduce at the negative terminal
    -the copper will be forced to oxidize at the positive terminal
    -having the steel connected to the negative terminal will protect it from being oxidized by the bleach
    -dissolved copper ions will be forced to reduce (turn into solid copper) at the negative terminal

    Much of this does happen. I know the copper is being oxidized because I can see it turning green on the surface and the solution itself turns green indicating copper(1) ions.

    Now here is the problem the copper that forms on the iron is not a plating; it is a crust. The copper can be easily wiped off with a rag!
    I've actually tried replacing the steel rod with a piece of carbon (which can be considered inert) and the same thing happens. Copper will form on the carbon but it can be wiped off with a rag very easily.

    I am aware that 12 volts is way too much but it's all I have. I've tried using 8 D size batteries in parallel but that doesn't work because the batteries run out of charge within 30 minutes.


    What am I doing wrong?


    btw I have done this before using a all the same supplies but I can't remember how the heck I did it.
     
    Last edited: Feb 23, 2004
  2. jcsd
  3. Feb 24, 2004 #2
    You said you've done this before, and I don't doubt you.
    It's just that as I recall (years ago, in highschool) when we did do the plating we were able to wipe it off pretty easily. In fact we would mass the amount of solid that had deposited on the cathode by removing it fairly easily. And it's also to my understanding that many many companies plate their jewelery using this very technique, however they are also in the presence of magical equipments and other things I could only dream of owning. I hope I'm not seeming offensive here. Anyway I'd be interested to hear what other people (chem tutor, chemsuperfreak) have to say about this.

    I'm sure I've been a tremondous help
     
  4. Feb 24, 2004 #3

    ShawnD

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    Science Advisor

    OK I remember what I did differently before. Before, I just let the bleach eat away the copper for a day then once all the bleach is gone, I would put the piece of steel in the solution and just let the copper replace the iron and nickel on the piece of steel. After the first coating of copper was on, I setup the electrolysis mentioned above and it plated the steel quite nicely.

    Since my first post, I've tried this method and it doesn't work like it did before. There are 2 main differences I have noticed that may be causing some problems:

    1. Before, the solution was a dark blue meaning it had lots of copper 2 ions. Now, the solution is dark green meaning it has lots of copper 1 ions.

    2. The temperature now is much colder than it was when I originally did this process. Yesterday, my bleach solution actually had ice forming on the top.


    Could the lower temperature and different ions be the cause of the problem?
     
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