6.7.4

Electrolytic Cells

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Electrolytic Cells

Electrochemical cells that undergo reactions that are not thermodynamically favorable are called electrolytic cells. They require an input of voltage for reacions to occur.

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Electrolytic cells

  • In galvanic cells, electrical work is done by a redox system on its surroundings.
    • Electrons produced by the redox reaction are transferred through an external circuit.
  • In electrolytic cells, an external circuit does work on a redox system by imposing a voltage sufficient to drive an otherwise thermodynamically unfavorable reaction.
    • This process is known as electrolysis.
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Example

  • Metallic sodium, Na, and chlorine gas, Cl2, are used in numerous applications.
  • Their industrial production relies on the large-scale electrolysis of molten sodium chloride, NaCl(l).
  • The reactions associated with this process are:
    • Anode: 2Cl(l)⟶Cl2(g) + 2e
    • Cathode: Na+(l) + e ⟶ Na(l)
    • Cell: 2Na+(l) + 2Cl(l) ⟶ 2Na(l) + Cl2(g)
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Applying voltage

  • The cell potential for the above process is negative.
  • This indicated that the reaction as written (decomposition of liquid NaCl) is not thermodynamically favorable.
    • To force this reaction, a positive potential of magnitude greater than the negative cell potential must be applied to the cell.

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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