The key difference between electrode potential and cell potential is that electrode potential refers to the ability of an electrode in a cell to get reduced or oxidized whereas cell potential is the difference between the electrode potentials of the electrodes present in an electrochemical cell.
Electrode potential and cell potential are terms that explain the electromotive force of an electrochemical cell. Electrode potential gives the voltaic potential of a single electrode while cell potential considers the electrode potentials of both electrodes.
CONTENTS
1. Overview and Key Difference
2. What is Electrode Potential
3. What is Cell Potential
4. Side by Side Comparison – Electrode Potential vs Cell Potential in Tabular Form
5. Summary
What is Electrode Potential?
Electrode potential is the tendency of an electrode in an electrochemical cell to get reduced or oxidized. It is the electromotive force of a cell. There are three factors affecting the value of the electrode potential: nature of the electrode, the concentration of the ions in the electrolytic solution and temperature. For any electrochemical cell, the total potential is the sum of electrode potentials of the two electrodes. We can denote the electrode potential as E. However, we cannot measure the electrode potential in isolation. It has to be measured in a reaction with some other electrode.
Figure 01: A Simple Electrochemical Cell
Moreover, the electrode potential depends on the concentrations of the electrodes, the temperature of the electrochemical cell, and also the pressure (if the cell contains gas electrodes). Generally, the electrode potentials are measured with respect to a standard electrode.
The typical standard electrode is the hydrogen electrode and its electrode potential is taken as zero. In addition, we must use standard thermodynamic conditions in order when measuring the potentials; otherwise, we cannot get the exact potential value since the electrode potential depends on the temperature, pressure, etc. Here, the standard thermodynamic conditions include measuring against a hydrogen electrode, an electrolytic solution having a concentration of 1 mol/L, pressure of 1 atm, and a temperature of 25°C.
What is Cell Potential?
Cell potential refers to the total voltaic potential of an electrochemical cell having two electrodes. Here, the electrochemical cells should have two separate half-reactions that take place parallel to each other and then, the cell potential is as follows:
Ecell = oxidation potential + reduction potential
Therefore, the cell potential is the sum of the cathode electrode potential and the anode electrode potential. A real voltaic cell differs from standard conditions. Therefore, we need to adjust the experimental value to get the standard value. It is as follows:
Ecell = E0cell – (RT/nF)lnQ
Where Ecell is the experimental cell potential, E0cell is the standard cell potential, R is the universal constant, T is the temperature, n is the moles of electrons exchanged in half-reactions, F is the Faraday constant and Q is the thermodynamic reaction quotient.
What is the Difference Between Electrode Potential and Cell Potential?
The key difference between electrode potential and cell potential is that electrode potential refers to the ability of an electrode in a cell to get reduced or oxidized whereas cell potential is the difference between the electrode potentials of the electrodes present in an electrochemical cell. Therefore, electrode potential gives the voltaic potential of a single electrode while cell potential considers both electrodes.
Moreover, another significant difference between electrode potential and cell potential is that it is impossible to measure the electrode potential because it is a relative value, but cell potential can easily be measured because we need to find the difference in electrode potentials, which are relative values.
Summary – Electrode Potential vs Cell Potential
Electrode potential and cell potential are discussed under electrochemistry, regarding electrochemical cells. The key difference between electrode potential and cell potential is that electrode potential refers to the ability of an electrode in a cell to get reduced or oxidized whereas cell potential is the difference between the electrode potentials of the electrodes present in an electrochemical cell.
Reference:
1. “Standard Electrode Potentials.” Hyperphysics, Available here.
Image Courtesy:
1. “Galvanic Cell” By Gringer – File:Galvanische Zelle.png, by Tinux (CC BY-SA 3.0) via Commons Wikimedia