Half-Cell Definition in Chemistry

Daniell Cell
Daniell cell electrochemistry may be written as two half-reactions.

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By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on January 13, 2020

A half-cell is half of an electrolytic or voltaic cell, where either oxidation or reduction occurs. The half-cell reaction at the anode is oxidation, while the half-cell reaction at the cathode is reduction.

Half-Cell Example

The electrochemical reaction of a Daniell cell may be written as two half-cells. The original equation is:

Battery driven by electrolyte concentrations porous vase version
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Galvanic Cell Definition (Voltaic Cell)
By Anne Marie Helmenstine, Ph.D.

2H+(aq) + 2e- → H2(g)

The half-cells or half-reactions are:

Zn → Zn2+ + 2e− (for the reaction at the anode or Zn)

Cu2+ + 2e− → Cu (for the reaction at the cathode or Cu)

Source

  • Andrews, Donald H.; Richard J. Kokes (1962). "Electrochemistry." Fundamental Chemistry. New York: John Wiley & Sons, Inc.
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Helmenstine, Anne Marie, Ph.D. "Half-Cell Definition in Chemistry." ThoughtCo, Feb. 16, 2021, thoughtco.com/definition-of-half-cell-604521. Helmenstine, Anne Marie, Ph.D. (2021, February 16). Half-Cell Definition in Chemistry. Retrieved from https://www.thoughtco.com/definition-of-half-cell-604521 Helmenstine, Anne Marie, Ph.D. "Half-Cell Definition in Chemistry." ThoughtCo. https://www.thoughtco.com/definition-of-half-cell-604521 (accessed April 25, 2024).