Standard electrode potential
Electrode potential measured under standard conditions (1 M concentration, 1 atm pressure for gases, 298 K).
What is Standard electrode potential?
The potential of a half-cell measured under standard conditions (298 K, 1 atm pressure for gases, 1 M concentration for solutions), relative to the standard hydrogen electrode.
Key formula / rule: Standard Cell Potential
Key points
- Define standard electrode potential and its significance.
- Identify the standard conditions for measuring electrode potentials.
- Explain the role of the Standard Hydrogen Electrode (SHE).
- Interpret the meaning of positive and negative standard electrode potentials.
Common exam trap
Confusing standard electrode potential with cell potential.
Definitions
- Term
Standard Electrode Potential (E°)
- Meaning
The potential of a half-cell measured under standard conditions (298 K, 1 atm pressure for gases, 1 M concentration for solutions), relative to the standard hydrogen electrode.
- Term
Standard Hydrogen Electrode (SHE)
- Meaning
A reference electrode with an assigned standard electrode potential of 0 volts, used to measure the potentials of other half-cells.
- Term
Standard Conditions
- Meaning
The specific conditions (298 K, 1 atm pressure, 1 M concentration) under which electrochemical potentials are measured and compared.
Learning objectives
Define standard electrode potential and its significance.
Identify the standard conditions for measuring electrode potentials.
Explain the role of the Standard Hydrogen Electrode (SHE).
Interpret the meaning of positive and negative standard electrode potentials.
Relate standard electrode potential to the ease of reduction and oxidation.
Formulae
- Name
Standard Cell Potential
- Note
Where E°cathode and E°anode are standard reduction potentials of the cathode and anode half-cells, respectively.
- Expression
E°cell = E°cathode - E°anode
- Name
Nernst Equation (at standard conditions)
- Note
This simplifies to E°cell when Q=1 (standard conditions).
- Expression
Ecell = E°cell - (RT/nF)lnQ
Prerequisites
Electrochemical cells
Redox reactions
Concentration and pressure
Standard Hydrogen Electrode (SHE)
Common mistakes
Confusing standard electrode potential with cell potential.
Forgetting to consider standard conditions when comparing potentials.
Incorrectly assigning signs to electrode potentials.
Assuming a reaction will occur spontaneously without considering standard conditions or concentrations.
Keywords
Standard Electrode Potential
Electrode Potential
Standard Conditions
Standard Hydrogen Electrode
SHE
Reduction Potential
Oxidation Potential
Electrochemical Cell
Spontaneity
Nernst Equation
Practice preview
Which of the following is NOT a standard condition for measuring electrode potential?…
easy
Consider the standard electrode potentials: E°(Zn²⁺/Zn) = -0.76 V and E°(Cu²⁺/Cu) = +0.34 V. What is the standard cell potential (E°cell) for the reaction Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)?…
medium
What are the standard conditions under which the electrode potential is measured?…
easy