Equilibrium Potential

Definition - What does Equilibrium Potential mean?

Equilibrium potential is the saturation of the momentary directional flow of charged ions at the cell membrane level. This phase typically features a zero charge inhibiting the flow of ions between either side of the membrane. However, the phase is independent of the ion flow on both sides of the membrane.

The equilibrium potential of an ion is calculated using the Nernst equation if the concentration gradient of the element is known. The cross-referencing of the ion potential to break the barrier with the help of the charge ascertains the threshold limit for the crossing of the membrane.

Corrosionpedia explains Equilibrium Potential

Equilibrium potential deals with the electrical potential difference across the membrane. The practical implementation of the equilibrium potential for anticorrosive properties is possible with the schematic calculations of the values and the influencing factors.

Consideration of equilibrium potential is vital during anticorrosive treatments. The achievement of the passivity of the metal greatly helps to prevent corrosion. Metal undergoes corrosion if the value of potential range is more positive than its equilibrium potential value. The metal does not corrode when the equilibrium potential is attained and there is no transfer of ions in either direction. Many factors govern these values, like:

  • The pH diagram - The nature of the surfaces under corrosion in aqueous solutions shows the fluctuations based on its acidity or the basicity. The pH diagram of the aqueous solution helps to determine the threshold values of the equilibrium potential, resulting in practical implementation of anticorrosive treatments.

  • Corrosion potential - The kinetics of metallic corrosion are highly influenced by the equilibrium potential and the corrosion potential. Cathodic and anodic oxidant reaction curves help to define the polarization curve of the corrosion. Understanding the role of equilibrium potential in this process becomes a definitive means for anticorrosive treatments.

The creation of hydroxides or metal oxides during the corrosion process is inhibited using the balance of the anodic oxidation with the cathodic oxidant reduction, which offers the control of anodic metal dissolution, and thus reduces metallic corrosion significantly. Thus, if the membrane potential is maintained at the specific equilibrium potential, the transfer of ions is not observed, resulting in complete corrosion resistance. However, in this situation, if the right value of the desired equilibrium potential is not maintained, it might mitigate corrosion due to the active transfer of the ions.

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