Galvanic (Voltaic) Electrochemical Cells |
Key Concepts
- Galvanic (Voltaic) Cell: converts chemical energy of oxidants and reductants into electrical energy
- Electrodes: are conductors used to permit the flow of electrons in an electrochemical cell.
One electrode is the anode, the other is the cathode.
- Anode: Oxidation occurs at anode
Anode is negative
Anode disintegrates
- Cathode:Reduction occurs at cathode
Cathode is positive
Solid deposits on cathode
- Salt bridge: allows for migration of ions to complete the electrical circuit
- Electron Flow: from anode to cathode
Electrons flow from negative to positive
- Spontaneous Reaction: E0 for the galvanic cell is positive
Flash Tutorial
Example : The Daniell Cell
A galvanic (voltaic) cell is a device that uses REDOX reactions to produce electricity.
In 1836 Professor John Daniell adopted a two-cell approach to produce electricity.
The Daniell Cell is divided into 2 half-cells connected by a wire and a salt bridge to complete the electrical circuit.
 |
| Anode: |
Zn |
---> |
Zn2+ + 2e |
Eo = +0.76V |
| Cathode: |
Cu2+ + 2e |
---> |
Cu |
Eo = +0.35V |
| |
|
| Cell: |
Zn + Cu2+ |
---> |
Zn2+ + Cu |
Eocell = +1.11V |
|
- At the negative anode, zinc is oxidised to zinc ions.
- The zinc anode disintegrates in time.
- At the positive cathode, copper ions are reduced to copper atoms.
- Copper is deposited on the copper cathode in time.
- Electrons flow from the zinc anode to the copper cathode.
- In the overall REDOX reaction zinc is donating electrons to copper ions.
- This REDOX reaction occurs spontaneously, Eo is positive.
- This REDOX reaction produces 1.11V of electricity.
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