Electrode potential
The potential difference developed between an electrode and its electrolyte solution.
What is Electrode potential?
The potential difference that develops between an electrode and the electrolyte solution in contact with it.
Key formula / rule: Nernst Equation
Key points
- Define electrode potential and explain its origin.
- Differentiate between oxidation and reduction potentials.
- Explain the concept of standard electrode potential.
- Identify factors affecting electrode potential.
Common exam trap
Confusing electrode potential with cell potential.
Definitions
- Term
Electrode Potential
- Meaning
The potential difference that develops between an electrode and the electrolyte solution in contact with it.
- Term
Standard Electrode Potential (E°)
- Meaning
The electrode potential measured when the concentration of the electrolyte is 1 M, the temperature is 298 K, and the pressure of any gas involved is 1 atm.
- Term
Standard Hydrogen Electrode (SHE)
- Meaning
A reference electrode with an assigned standard electrode potential of 0 V, used to measure the electrode potentials of other half-cells.
- Term
Oxidation Potential
- Meaning
The potential associated with the process of oxidation at an electrode.
- Term
Reduction Potential
- Meaning
The potential associated with the process of reduction at an electrode.
Learning objectives
Define electrode potential and explain its origin.
Differentiate between oxidation and reduction potentials.
Explain the concept of standard electrode potential.
Identify factors affecting electrode potential.
Understand the role of the Standard Hydrogen Electrode (SHE).
Formulae
- Name
Nernst Equation
- Note
Where E is electrode potential, E° is standard electrode potential, R is gas constant, T is temperature, n is number of electrons transferred, F is Faraday constant, and Q is reaction quotient.
- Expression
E = E° - (RT/nF)ln(Q)
- Name
Nernst Equation (at 298K)
- Note
Simplified form of Nernst equation at standard temperature (298K).
- Expression
E = E° - (0.0592/n)log(Q)
Prerequisites
Basic understanding of atomic structure and electron configuration.
Knowledge of oxidation and reduction reactions.
Concept of ions and electrolytes.
Understanding of electrochemical cells.
Common mistakes
Confusing electrode potential with cell potential.
Assuming electrode potential is independent of concentration.
Incorrectly applying the Nernst equation.
Not considering the standard conditions when referring to E°.
Keywords
Electrode potential
Standard electrode potential
Nernst equation
Oxidation
Reduction
Electrochemical cell
SHE
Half-cell potential
Practice preview
The standard electrode potential is measured under which of the following conditions?…
easy
Which of the following is an example of an electrode potential?…
medium
Which statement correctly describes the relationship between electrode potential and the tendency for oxidation/reduction?…
medium