Summary
Highlights
Electroplating is the process of coating one metal object with another using electrolysis, where electricity drives a chemical reaction. Metals are electroplated for aesthetics, like making jewelry shinier with gold or silver, and for protection against corrosion, rust, or wear and tear, as seen with car rims. Common plating metals include chromium, nickel, tin, zinc, and cadmium, often applied to copper, iron, and steel.
Electroplating involves passing an electric current through an electrolyte solution to create a current. Two electrodes (an anode and a cathode) are submerged in the electrolyte and connected to a power supply. The anode is positively charged, and the cathode is negatively charged. The chosen metal for plating typically forms the anode, and the object to be plated acts as the cathode. The electrolyte solution contains ions of the plating metal.
In copper plating, a copper anode, a brass cathode, and a copper sulfate electrolyte solution are used. Positively charged copper ions in the solution are attracted to the negatively charged brass cathode, gaining electrons (reduction) and depositing as a thin copper plate. Simultaneously, negatively charged sulfate ions are attracted to the copper anode, where copper atoms lose electrons (oxidation) and dissolve into the electrolyte, replenishing the copper ions.
Oxidation (loss of electrons) occurs at the anode, while reduction (gain of electrons) occurs at the cathode. The speed of electroplating is determined by the strength of the electric current, which can be increased by a higher concentration of ions in the solution. It's crucial to select compatible metals as not all metals will alloy directly; for example, steel needs to be copper-plated before silver-plating.
Environmental concerns exist with some electroplating processes, such as chrome plating, which generates hazardous waste requiring costly treatment. For current to flow, the compound must be molten or dissolved. In summary, electroplating uses electrolysis where positive ions move to the negative cathode, gain electrons (reduction) to form the plating, while metal atoms at the anode lose electrons (oxidation) and dissolve into the solution.