IB Understanding
Voltaic Cell Energy Conversion
A voltaic (galvanic) cell converts chemical energy released in a spontaneous redox reaction into electrical energy. The two half-cells are connected externally by a wire (electron flow) and internally by a salt bridge (ion flow).
Voltaic Cell (Zn/Cu)
Key Components
| Component | Function |
|---|---|
| Anode (−) | Oxidation occurs, electrons leave here |
| Cathode (+) | Reduction occurs, electrons arrive here |
| Salt bridge | Completes circuit; allows ion flow to balance charges |
| External wire | Allows electron flow generating current |
IUPAC Notation
Standard Cell Diagram Convention
Standard IUPAC cell notation for the Zn-Cu cell:
\[\mathbf{\text{Zn(s)} \mid \text{Zn}^{2+}\text{(aq)} \parallel \text{Cu}^{2+}\text{(aq)} \mid \text{Cu(s)}}\]- Single line \((\mid)\) = phase boundary.
- Double line \((\parallel)\) = salt bridge.
- Anode (oxidation) written on the left; Cathode (reduction) on the right.
Exam Tip
AN OX and RED CAT Mnemonics
Memory mnemonics:
- AN OX: Anode = Oxidation (negative in voltaic)
- RED CAT: Reduction = Cathode (positive in voltaic)
- Electrons always flow from Anode → Cathode through the wire.
AQA GCSE & IB Chemistry
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