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Please help! I was working on a mock research project/lab for my chemistry class testing the rate of electroplating of copper vs. voltage. I had copper and nickel electrodes and .1M copper sulfate solution. I made a huge mistake, however, and plugged the positive end into my nickel electrode and the negative end into the copper. This meant that the copper in solution was attracted to the copper electrode, not the nickel. I however, didn't notice because as I ran more and more trials, an orange buildup was in fact showing up on my nickel electrode that looked just like copper plating. When I measured the mass, however, of the nickel electrodes, they consistently went down (the higher the voltage, the bigger the difference). What happened? Why did the mass of the nickel electrode go down (shouldn't it have stayed the same)? What was being plated onto the nickel?

Thank you!

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    $\begingroup$ Your anode was nickel, by mistake. It was being oxidized and started to dissolved. Nothing surprising rather. The color on nickel could be a very thin film of copper deposited from reduction of copper ions on the nickel surface. Nickel is above copper in electrochemical series. $\endgroup$ – M. Farooq Nov 20 '19 at 1:12