Faraday's laws of electrolysis

Michael Faraday.

Faraday's laws of electrolysis are quantitative relationships based on the electrochemical researches published by Michael Faraday in 1834.[1] In the same years, in Italy, Carlo Matteucci discovered the laws of electrolysis by a method totally independent Faraday's methods. The laws of electrolysis can also be called Faraday-Matteucci's laws.

Mathematical form

Faraday's laws can be summarized by

m \ = \ \left({ Q \over F }\right)\left({ M \over z }\right)

where:

Note that M/z is the same as the equivalent weight of the substance altered.

For Faraday's first law, M, F, and z are constants, so that the larger the value of Q the larger m will be.

For Faraday's second law, Q, F, and z are constants, so that the larger the value of M/z (equivalent weight) the larger m will be.

In the simple case of constant-current electrolysis,  Q = I t leading to

m \ = \ \left({ I t\over F }\right)\left({ M \over z }\right)

and then to

n \ = \ \left({ I t\over F }\right)\left({ 1 \over z }\right)

where:

In the more complicated case of a variable electric current, the total charge Q is the electric current I(\tau) integrated over time \tau:

 Q = \int_0^t I(\tau) \ d \tau

Here t is the total electrolysis time.[2]

See also

References

  1. Ehl, Rosemary Gene; Ihde, Aaron (1954). "Faraday's Electrochemical Laws and the Determination of Equivalent Weights". Journal of Chemical Education 31 (May): 226232. Bibcode:1954JChEd..31..226E. doi:10.1021/ed031p226.
  2. For a similar treatment, see Strong, F. C. (1961). "Faraday's Laws in One Equation". Journal of Chemical Education 38 (2): 98. Bibcode:1961JChEd..38...98S. doi:10.1021/ed038p98.

Further reading

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