Electrochemical Cells
Year 11 (IGCSE) 🧪 Acids, Bases & Salts Describe galvanic cells; write half-equations; calculate cell EMF.
🔋 Galvanic Cells
A galvanic cell converts spontaneous chemical (redox) energy to electrical energy.
Cell EMF
$$E^\circ_\text{cell} = E^\circ_\text{cathode} - E^\circ_\text{anode}$$Zinc-copper cell: E°(Zn²⁺/Zn) = −0.76 V; E°(Cu²⁺/Cu) = +0.34 V
E°cell = +0.34 − (−0.76) = +1.10 V
E°cell = +0.34 − (−0.76) = +1.10 V
⚗️ Electrode Reactions
| Electrode | Process | Example |
|---|---|---|
| Anode (−) | Oxidation (OIL) | Zn → Zn²⁺ + 2e⁻ |
| Cathode (+) | Reduction (RIG) | Cu²⁺ + 2e⁻ → Cu |
Remember: "An Ox, Red Cat" — Anode = Oxidation, Cathode = Reduction.
🔌 Salt Bridge & Rechargeable Cells
Salt bridge (e.g. KNO₃ in agar): allows ions to flow between half-cells, maintaining electrical neutrality.
Rechargeable batteries (Li-ion, NiMH): during charging, electrical energy forces the non-spontaneous reverse reaction.
Ready to test yourself? Click the Quiz tab above to practise questions on this topic!
Interactive Demonstration — Electrochemical Cells
A simple electrochemical cell converts chemical energy to electrical energy.
🔋 Cell EMF Calculator
Calculate cell EMF from standard electrode potentials.