Science
Electrolysis.
Definition
Electrolysis is the process of using electrical energy to drive a non-spontaneous chemical reaction. An external power source forces electrons through an electrolyte solution, causing reduction at the cathode and oxidation at the anode.
How it works · 4 phases
Step by step.
- An external power source (battery or DC supply) is connected to two electrodes immersed in an electrolyte.
- Cations migrate to the cathode (negative electrode) where they gain electrons (reduction).
- Anions migrate to the anode (positive electrode) where they lose electrons (oxidation).
- The non-spontaneous reaction proceeds as long as electrical energy is supplied.
Examples
Real-world.
- 1 Electrolysis of water (2H₂O → 2H₂ + O₂) produces hydrogen and oxygen gas
- 2 Electroplating uses electrolysis to coat objects with a thin layer of metal like gold or chrome
- 3 Aluminum is industrially extracted from bauxite ore using the Hall-Héroult electrolysis process
Key Fact
Electrolysis requires energy input (non-spontaneous, ΔG > 0); galvanic cells release energy (spontaneous, ΔG < 0).