Problems in Copper and Zinc Electroplating

[hojess02]

TL;DR

Hi~
Pic 1: The first time we electroplated iron nail with copper. The surface of the nail had black substance after electroplating it.
Pic 2: The second time we did it & we used a lower concentration of copper(II) sulphate as electrolyte.

I wonder is that black substance copper oxide & what is the relationship between that black substance and the concentration of copper(II) sulphate.

Thanks!!

 

[hojess02]

 

[berkeman]

Welcome to PF.

Can you say more about your plating setup? What settings are you using? How long are you letting the plating process run?

 

[chemisttree]

Cu plating on an iron nail is spontaneous. You shouldn’t have needed any current. What was the other electrode made of? Were those galvanized nails?

 

[Borek]

Cu plating on an iron nail is spontaneous.

With current the process can be definitely speed up (and you can plate much thicker layers).

 

[hojess02]

Welcome to PF.

Can you say more about your plating setup? What settings are you using? How long are you letting the plating process run?

We used 3.0V (combination of two 1.5V batteries), copper plate, iron nail, 2 wires with crocodile clips, copper(II) sulphate solution (about 0.5M) (We didn't measure the concentration precisely) ThxThx

 

[hojess02]

Cu plating on an iron nail is spontaneous. You shouldn’t have needed any current. What was the other electrode made of? Were those galvanized nails?

I see... Is zinc electroplating on iron spontaneous too? Since zinc has a more negative standard electrode potential. Those were non-galvanized nails.

 

[hojess02]

With current the process can be definitely speed up (and you can plate much thicker layers).

I see... thanks!

 

[chemisttree]

You are using two iron nails for electrodes. Only one will produce copper. Which one is black? Anode or cathode?

 

[Borek]

You are using two iron nails for electrodes. Only one will produce copper. Which one is black? Anode or cathode?

There is a problem with OP post formatting, but I believe they used copper plate for the anode.