What to do: Prepare the key for copper-plating by cleaning it. Stircopper sulfate into some hot water in a beaker until no more will dissolve. Your solution should be dark blue. Let it cool.
Attach the copper electrode to the positive terminal of the battery (this is now the anode) and the other to attach the key to the negative terminal (now called the cathode). Partially suspend the key in the solution
Place the copper strip into the solution, making sure it doesnt touch the key . An electrical circuit has now formed and current is flowing. Leave the circuit running for 20-30 minutes, or until you are happy with the amount of copper on the key.
What Happens…. The copper sulfate solution is an electrolyte that conducts electricity from one electrode to the other. When the current is flowing, oxidation (loss of electrons) happens at the copper anode, adding copper ions to the solution.
Thoseions travel on the electric current to the cathode, where reduction (gain of electrons) happens, plating the copper ions onto the key.