6.7.2

Galvanic Cells

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Galvanic Cells

Electrochemical cells in which a thermodynamically favored redox reaction takes place are called galvanic cells.

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Example

  • A galvanic cell based on the spontaneous reaction between copper and silver(I) is depicted in the image above and repeated on the next slide.
  • The cell is comprised of two half-cells, each containing the redox conjugate pair (“couple”) of a single reactant.
    • The half-cell shown at the left contains the Cu(0)/Cu(II) couple in the form of a solid copper foil and an aqueous solution of copper nitrate.
    • The right half-cell contains the Ag(I)/Ag(0) couple as solid silver foil and an aqueous silver nitrate solution.
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Components of galvanic cells

  • The anode of an electrochemical cell is the electrode at which oxidation occurs (in this case, the Cu foil).
  • The cathode is the electrode where reduction occurs (the Ag foil).
  • The redox reactions in a galvanic cell occur only at the interface between each half-cell’s reaction mixture and its electrode.
    • To keep the reactants separate while maintaining charge-balance, the two half-cell solutions are connected by a tube filled with inert electrolyte solution called a salt bridge.
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Reaction

  • The thermodynamically favorable reaction in this cell:
    • Produces Cu2+ cations in the anode half-cell.
    • Consumes Ag+ ions in the cathode half-cell.
  • This results in a compensatory flow of inert ions from the salt bridge that maintains charge balance.
  • Increasing concentrations of Cu2+ in the anode half-cell are balanced by an influx of NO3− from the salt bridge.
  • A flow of Na+ into the cathode half-cell compensates for the decreasing Ag+ concentration.

Jump to other topics

1Structure - Models of the Particulate of Matter

2Structure - Models of Bonding & Structure

3Structure - Classification of Matter

3.1The Periodic Table: Classification of Elements

3.2Periodic Trends

3.3Group 1 Alkali Metals

3.4Halogens

3.5Noble gases, group 18

3.6Functional Groups: Classification of Organic

3.7Functional Group Chemistry

3.8Alkanes

3.9Alcohols

3.10Halogenoalkanes

4Reactivity - What Drives Chemical Reaction?

5Reactivity - How Much, How Fast & How Far?

6Reactivity - The Mechanisms of Chemical Change

7Measurement, Data Processing & Analysis

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