Introduction
Electrolysis is widely applied in industries for extraction of reactive metals, purification of metals, and decorative or protective plating. Mastering these applications is essential for understanding industrial chemistry and real-world uses of redox reactions.
🔹 1. Electrolysis in Metal Extraction
Used for highly reactive metals (e.g., aluminium, sodium, magnesium) that cannot be reduced using carbon.
Example: Extraction of Aluminium (Hall-Héroult process)
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Ore: Bauxite (Al₂O₃·xH₂O)
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Electrolyte: Molten cryolite + aluminium oxide
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Electrodes: Carbon anode and cathode
At cathode:
At anode:
🔥 Carbon anodes react with oxygen:
✅ Aluminium is collected at cathode as molten metal
🔹 2. Electrorefining (Purification of Metals)
Used to purify impure metals such as copper, zinc, silver.
Example: Electrorefining of Copper
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Anode: Impure copper
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Cathode: Pure copper strip
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Electrolyte: Copper(II) sulfate (CuSO₄)
At anode:
At cathode:
🔧 Impurities fall below the anode as anode sludge
✅ Used in electrical wiring and electronics industries
🔹 3. Electroplating (Coating Metals)
Used to coat cheaper metals with thin layers of expensive or corrosion-resistant metals.
Example: Silver Plating a Spoon
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Anode: Pure silver
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Cathode: Metal spoon (to be plated)
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Electrolyte: AgNO₃ solution
At anode:
At cathode:
✅ Result: The spoon is coated with shiny silver
🔹 4. Industrial Uses Summary
Application | Process | Example Materials |
---|---|---|
Metal extraction | Electrolysis of ores | Al, Na, Mg |
Refining | Electrorefining | Cu, Zn, Ag |
Electroplating | Metal coating | Ag, Cr, Au, Ni |
Chloralkali | Brine electrolysis | NaOH, Cl₂, H₂ |
🧠 NECTA Tips
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Always specify anode and cathode materials
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Write correct half-equations
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Link product to its real-world use
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Be ready to label or draw industrial setups
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Know which metals require electrolysis for extraction (high in reactivity series)
✅ Summary
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Electrolysis is vital for modern metallurgy and manufacturing
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Used in extracting reactive metals, purifying metals, and coating surfaces
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Requires understanding of half-equations, electrode roles, and setup
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Common in NECTA theory, essay, and structured questions