These half-cell potentials are defined relative to the assignment of 0 volts to the standard hydrogen electrode ( SHE ) . ( See table of standard electrode potentials ).
32.
When a current flows in the circuit, equilibrium conditions are not achieved and the cell potential will usually be reduced by various mechanisms, such as the development of overpotentials.
33.
Since the electrode potentials are conventionally defined as reduction potentials, the sign of the potential for the metal electrode being oxidized must be reversed when calculating the overall cell potential.
34.
When a cell has significant permeabilities to more than one ion, the cell potential can be calculated from the Goldman-Hodgkin-Katz equation rather than the Nernst equation.
35.
Silver / silver chloride is a popular choice of biological electrodes due to its low half-cell potential of approximately 220 mV and the lower of the impedance of the electrode by silver chloride.
36.
In the DC system that is used by the ECG and EEG instruments, the difference between the half-cell potential and the zero potential is shown as DC offset which is an undesirable characteristic.
37.
The thermodynamic standard cell potential can be obtained from standard-state free energy calculations to find ?G?and then using the equation : ?G?=-nFE?( where E?is the cell potential ).
38.
The thermodynamic standard cell potential can be obtained from standard-state free energy calculations to find ?G?and then using the equation : ?G?=-nFE?( where E?is the cell potential ).
39.
However, the total cell potential ( difference between oxidation and reduction half cell potentials ) will remain 1.23 V . This potential can be related to Gibbs free energy ( ?G ) by:
40.
However, the total cell potential ( difference between oxidation and reduction half cell potentials ) will remain 1.23 V . This potential can be related to Gibbs free energy ( ?G ) by:
