Chemical changes occur when the copper atoms on the surface of the penny are oxidized to copper ions, which then react with gold ions in the plating solution to form gold atoms. These gold atoms deposit on the surface of the penny, creating a thin layer of gold.
Electrical changes occur when an electrical current is passed through the plating solution, causing the copper ions to migrate to the cathode (the negatively charged electrode), while the gold ions migrate to the anode (the positively charged electrode). This movement of ions is what drives the chemical reactions that result in the formation of the gold layer.
