Galvanic (Voltaic) and Electrolytic Cells
Electrochemistry studies redox reactions and the flow of electrons. Two main types of cells are used to harness or drive these reactions: galvanic (voltaic) cells and electrolytic cells.
Galvanic (Voltaic) Cells
- Purpose: Generate electrical energy from spontaneous redox reactions.
- Components:
- Anode: site of oxidation (electrons lost)
- Cathode: site of reduction (electrons gained)
- Salt bridge: maintains charge balance by allowing ion flow
- Electron flow: From anode → external circuit → cathode
- Cell potential (E°cell): Positive for spontaneous reactions
- Example: Daniell cell
Electrolytic Cells
- Purpose: Use electrical energy to drive non-spontaneous reactions.
- Components: Similar to galvanic cells but powered by an external voltage source
- Electron flow: From negative terminal → anode → cathode → positive terminal
- Cell potential (Ecell): Negative without external power
- Example: Electrolysis of molten NaCl
Key Differences
| Feature | Galvanic Cell | Electrolytic Cell |
|---|---|---|
| Reaction | Spontaneous | Non-spontaneous |
| Energy Flow | Chemical → Electrical | Electrical → Chemical |
| Anode | Negative | Positive |
| Cathode | Positive | Negative |
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