5.4C - Electroplating to improve metal objects
Electroplating deposits a thin metal coating on an object. You will connect the cell arrangement and electron transfer with improved appearance, lower material cost and resistance to corrosion.
Why coat an object with metal?
Electroplating
Electroplating uses electrolysis to coat an object with a thin layer of another metal.
The outside surface can have useful properties while the metal underneath provides strength or keeps the cost down. A thin gold coating gives jewellery a gold appearance using much less gold than a solid-gold object. A suitable corrosion-resistant coating can protect the base metal.
The coating is solid metal deposited using an electric current, not paint or crystals left by evaporating a solution.
How the coating forms
The object to be plated connects to the negative terminal of a d.c. supply: it is the cathode. It is immersed in an electrolyte containing ions of the plating metal. In the silver-plating arrangement shown, a silver anode connects to the positive terminal.
[DIAGRAM: asset_name: Electroplating arrangement - diagram 1; asset_slug: 123_5_4c_electroplating_can_be_used_to_improve_the_appearance_and_or_the_resistance_diagram1; file: 123_5_4c_electroplating_can_be_used_to_improve_the_appearance_and_or_the_resistance_diagram1_imagegen_v1.png; recommended_method: deterministic_drawn; description: Monochrome exact teaching diagram of an electroplating cell. Show a d.c. power supply connected to a positive silver metal anode and a negative metal object cathode in an electrolyte containing Ag+ ions. Show Ag+ ions moving towards the cathode, a thin silver coating forming on the object, and the cathode half-equation Ag+ + e- -> Ag. This is an assessed/exact apparatus-and-process visual; labels must be readable and the diagram must not use colour coding.]
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