I have a connector with two pins - power and ground. The pins are made of copper, coated with nickel, and then coated with gold.

When I apply NaCl solution across both pins and a potential across the pins, I notice corrosion immediately start to occur. I see the presence of "blue" corrosion, which I'm assuming is Copper(II) chloride and bubbles. In this case, I believe the copper is losing electrons and forming Cu2+, which combines with the Cl- ions in my "salt bridge". What part of the setup is gaining electrons and what products am I forming?

After left for some time, the solution has evaporated and I'm left with some white residue on the ground pin. Is it safe to say that the white reside is most likely Na+ ions on the pin? My reasoning for this is because the Cl- ions from the salt bridge migrate to the higher potential cell, therefore, the Na+ must migrate to the lower potential cell to equilibrate charge.

Thanks in advance for your help.