Question:
Write the definition of electrode potential and cell electromotive force (emf).
Write the definition of electrode potential and cell electromotive force (emf).
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Key difference: Cell Potential is measured when the circuit is closed (current flows), whereas EMF is measured when the circuit is open (no current flows). EMF is always slightly higher than cell potential due to internal resistance.
Updated On: Feb 26, 2026
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Solution and Explanation
1. Electrode Potential:
When a metal rod is dipped into a solution of its own ions, a potential difference develops at the interface between the metal electrode and the electrolyte (solution). This potential difference is called the Electrode Potential.
The electromotive force (emf) of a cell is the potential difference between the two electrodes of a galvanic cell when no current is drawn from the cell (open circuit). It is the maximum voltage the cell can deliver. \[ E_{cell} = E_{cathode} - E_{anode} \]
When a metal rod is dipped into a solution of its own ions, a potential difference develops at the interface between the metal electrode and the electrolyte (solution). This potential difference is called the Electrode Potential.
- If the metal has a tendency to oxidize (lose electrons), it is Oxidation Potential.
- If metal ions have a tendency to reduce (gain electrons), it is Reduction Potential.
The electromotive force (emf) of a cell is the potential difference between the two electrodes of a galvanic cell when no current is drawn from the cell (open circuit). It is the maximum voltage the cell can deliver. \[ E_{cell} = E_{cathode} - E_{anode} \]
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