A polarizable electrode is characterized by charge separation at the electrode-electrolyte boundary and behaves like a capacitor. It does not allow faradic current to pass freely and the electrode reaction is very slow. In contrast, a non-polarizable electrode does not exhibit charge separation and allows faradic current to pass through without polarization. It has an infinitely fast electrode reaction and behaves like a resistor. Examples of polarizable electrodes include platinum while silver/silver chloride is an example of a non-polarizable electrode.

1. POLARIZABLE AND NON-POLARIZABLE ELECTRODES
NAME: TALHA LIAQAT
Reg. No: Chem18111035
BS CHEMISTRY 7TH Analytical
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2. • Polarizable Electrode
• A polarizable electrode is an electrode in an electrochemical
cell that is characterized by charge separation at the electrode-
electrolyte boundary.
• A polarizable electrode is electrically equivalent to a capacitor.
• An ideal polarizable electrode is a hypothetical substance that
is characterized by the absence of a net DC current between
the two sides of the electrical double layer.
• In other words, there is no faradic current existing between the
electrode surface and the electrolyte.
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3. • Polarizable Electrode
• Therefore, any transient current that is flowing through
this system is considered as non-faradic current.
• This behaviour is due to electrode reaction being
infinitely slow, having a zero exchange current density,
making it behave as a capacitor by means of electricity.
• The platinum electrode is a classic example of a
polarizable electrode.
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4. • Ideal Polarizable Electrode
• A small current generates a high potential across it (i.e., the
interface is polarized to a large extent).
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5. • Non-Polarizable Electrode
• A non-polarizable electrode is an electrode in an
electrochemical cell that can be characterized by no charge
separation at the electrode-electrolyte boundary.
• That means the electrochemical cells having these electrodes
have faradic current that can freely pass without polarization.
• An ideal non-polarizable electrode is a hypothetical electrode
having this property of not having a charge separation.
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6. • Non-Polarizable Electrode
• The potential of a non-polarizable electrode does
not change from its equilibrium potential upon the
application of a current.
• This type of electrodes can behave as an electrical
shot.
• We can observe the reason for this behaviour as the
infinitely fast electrode reaction that has an infinite
exchange current density.
• Silver/silver chloride electrode is a classic
example of a non-polarizable electrode.
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7. • Ideal Non-Polarizable Electrode
• A non-polarizable electrode has no polarization means current
flows freely and the electrode-electrolyte interface behaves like a
resistor.
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8. Properties Polarizable Electrode Non-Polarizable Electrode
Charge Separation Characteristic Absent
Faradic current No Faradic Current Exists A faradic current freely passes through
system
Electrode Reaction Very Slow Very Fast
Exchange Current Density Nearly zero Nearly Infinite
Behaviour Similar to a capacitor Similar to an Electrical Shot
Examples Platinum Electrodes Silver/Silver
Chloride Electrode
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