IB Understanding
Purpose and Process of Electroplating
Electroplating is an electrolytic process in which a layer of metal (such as silver, gold, chromium, or nickel) is deposited onto the surface of a conductive object for corrosion protection, wear resistance, or aesthetic appearance.
How Electroplating Works
Apparatus
Electroplating Setup Checklist
- Cathode (−): The object to be plated (metal ions gain electrons and deposit as solid metal).
- Anode (+): A piece of the coating metal (oxidises to replenish metal ions in solution).
- Electrolyte: Aqueous salt solution containing the metal ions being plated (e.g. \(\text{AgNO}_3(\text{aq})\)).
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
Examiner Trap
Cathode Object Placement
The object being plated is always the cathode (−). If you make it the anode, the object will dissolve instead of being plated!
AQA GCSE & IB Chemistry
See our apps
Study this topic on the go
Get active recall flashcards, notes, and topic quizzes in ChemEasy, or build your revision schedule with ChemPlan IB.