📘 IB Understanding
Electroplating is a specific application of electrolysis where a thin, uniform layer of metal is deposited onto the surface of another object to improve its appearance, corrosion resistance, or durability.
How Electroplating Works
Setup
- Cathode (-): the object to be plated
- Anode (+): the plating metal (e.g. silver, chromium)
- Electrolyte: a solution containing ions of the plating metal
Example: Silver Plating
| At the... | Half-equation | Process |
|---|---|---|
| Anode (Ag bar) | Ag(s) → Ag+(aq) + e- | Oxidation: silver dissolves |
| Cathode (object) | Ag+(aq) + e- → Ag(s) | Reduction: silver coats object |
Applications
- Jewellery: Gold or silver plating for aesthetic appeal
- Cutlery: Silver plating for corrosion resistance
- Car bumpers: Chromium plating for a shiny, durable finish
- Electronics: Copper or gold plating for conductivity
Factors Affecting Plating Quality
- Current: higher current gives a faster but rougher coating
- Time: longer time gives a thicker coating
- Temperature: affects deposition rate and crystal structure
- Concentration: electrolyte concentration affects uniformity
⚠️ Exam Tip
The plating metal must be the anode so it dissolves into solution and maintains the concentration of metal ions.