Galvani Potential - Relation To Measured Cell Potential

Relation To Measured Cell Potential

The Galvani potential difference is not measurable. The measured potential difference between two metal electrodes assembled into a cell does not equal the difference of the Galvani potentials of the two metals (or their combination with the solution Galvani potential) because the cell needs to contains another metal-metal interface, as in the following schematic of a galvanic cell:

M(1) | S | M(2) | M(1)'

where:

  • M(1) and M(2) are the two different metals,
  • S denotes the electrolyte,
  • M(1)' is the additional metal (here assumed to be the metal (1)) that must be inserted into the circuit to close it,
  • the vertical bar, |, denotes a phase boundary.

Instead, the measured cell potential can be written as:

E^{(2)} - E^{(1)} = \left(\phi^{(2)} - \phi^{(S)} - \frac {\mu_j^{(2)}} {z_j F}\right) - \left(\phi^{(1)} - \phi^{(S)} - \frac {\mu_j^{(1)}} {z_j F}\right) = \left(\phi^{(2)} - \phi^{(1)}\right) - \left(\frac {\mu_j^{(2)} - \mu_j^{(1)}} {z_j F}\right)

where:

  • E is the potential of a single electrode,
  • (S) denotes the electrolyte solution.

From the above equation, two metals in electronic contact (i.e., under electronic equilibrium) must have the same electrode potential. Also, the electrochemical potentials of the electrons within the two metals will be the same. However, their Galvani potentials will be different (unless the metals are identical).

Read more about this topic:  Galvani Potential

Famous quotes containing the words relation to, relation, measured, cell and/or potential:

    “The whole point of Camp is to dethrone the serious. Camp is playful, anti-serious. More precisely, Camp involves a new, more complex relation to “the serious.” One can be serious about the frivolous, frivolous about the serious.”
    —Susan Sontag (b. 1933)

    “Among the most valuable but least appreciated experiences parenthood can provide are the opportunities it offers for exploring, reliving, and resolving one’s own childhood problems in the context of one’s relation to one’s child.”
    —Bruno Bettelheim (20th century)

    “Measured by any standard known to science—by horse-power, calories, volts, mass in any shape,—the tension and vibration and volume and so-called progression of society were full a thousand times greater in 1900 than in 1800;Mthe force had doubled ten times over, and the speed, when measured by electrical standards as in telegraphy, approached infinity, and had annihilated both space and time. No law of material movement applied to it.”
    —Henry Brooks Adams (1838–1918)

    “Women have no wilderness in them,
    They are provident instead,
    Content in the tight hot cell of their hearts
    To eat dusty bread.”
    —Louise Bogan (1897–1970)

    “The real community of man ... is the community of those who seek the truth, of the potential knowers.”
    —Allan Bloom (1930–1992)