What is polarization and overvoltage?

Polarization is the change of potential from a stabilized state, e.g. from the open-circuit electrode potential as the result of the passage of current. Often accomplished by formation of a film on the electrode surface. Polarization is sometimes also referred to as “overvoltage” or “overpotential”.

What is the difference between overvoltage and overpotential?

Overpotential: The difference in the electrode potential of an electrode between its equilibrium potential and its operating potential when a current is flowing. Overvoltage: The difference between the cell voltage (with a current flowing) and the open-circuit voltage (ocv).

What is the relation between polarization and overpotential?

Activation polarization is the overpotential (change of the electrode potential) caused by overcoming the energy barrier of the slowest step of the electrochemical reaction.

What do you mean by concentration polarization?

Concentration polarization occurs when the concentration of a specific component increases or decreases at the boundary layer close to the membrane surface due to the selective transport through the membrane. This profile can be also found in processes such as membrane-based extraction or membrane-based absorption.

What is cathodic overvoltage?

Cathodic overvoltage : It is the potential which is in excess of the reversible discharge potential cations at cathodic surface. For reversible discharge of cation Ed > > Er.

What is overvoltage in electrochemistry Class 12?

Overpotential is an electrochemical term which directs to the voltage difference (potential) between a Half- Cell reaction’s thermodynamically determined reduction potential and the potential at which the redox event is experimentally observed.

What causes overvoltage?

Cause of overvoltage in power/electrical system External overvoltage happens due to lightning and atmospheric changes. Whereas internal overvoltage happens due to internal operation mood of the system. Internal overvoltages are dividing into power frequency overvoltage, operation overvoltage and resonances overvoltage.

What is overvoltage in power systems?

Overvoltage happens in a condition where the voltage is increased and exceed its design limit. This situation may lead to harmful damage to machines or related equipment that connected to the system. Overvoltage can exist in a form of transient, voltage spike or permanent, depending on its duration.

What are the factors that affect the concentration polarization?

The magnitude of RC depends on several factors affecting the thickness and permeability of the concentration polarisation layer, such as the transmembrane pressure, cross-flow velocity, fluid viscosity, temperature, and solute concentration.

How do you find polarization concentration?

A mathematical model is provided to calculate dependences of a concentration polarization coefficient (ζ s) on a volume flux (J vm), an osmotic force (Δπ) and a hydrostatic force (ΔP) of different values. Property ζ s = f(J vm) for J vm > 0 and for J vm ≈ 0 and property ζ s = f(ΔC 1) are calculated.