**Faraday's laws of electrolysis** are quantitative relationships based on the electrochemical research published by Michael Faraday in 1833.^{[1]}^{[2]} ^{[3]}

## First law

Michael Faraday reported that the mass() of elements deposited at an electrode is directly proportional to the charge ( in ampere seconds or coulombs).^{[3]}

Here, the constant of proportionality is called the electro-chemical equivalent (e.c.e) of the substance. Thus, the e.c.e. can be defined as the mass of the substance deposited/liberated per unit charge.

## Second law

Faraday discovered that when the same amount of electric current is passed through different electrolytes/elements connected in series, the mass of the substance liberated/deposited at the electrodes in g is directly proportional to their chemical equivalent/equivalent weight ().^{[3]} This turns out to be the molar mass () divided by the valence ()

- (From 1st Law)

## Derivation

A monovalent ion requires 1 electron for discharge, a divalent ion requires 2 electrons for discharge and so on. Thus, if electrons flow, atoms are discharged.

So the mass discharged

(where is the Avogadro constant)

(From *Q* = *xe*)

Where () is the Faraday constant.

## Mathematical form

Faraday's laws can be summarized by

where is the molar mass of the substance (in grams per mol) and is the valency of the ions .

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

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

In the simple case of constant-current electrolysis, leading to

and then to

where:

*n*is the amount of substance ("number of moles") liberated:*n = m/M**t*is the total time the constant current was applied.

For the case of an alloy whose constituents have different valencies, we have

where *w _{i}* represents the mass fraction of the

*i*

^{th}element.

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

Here *t* is the *total* electrolysis time.^{[4]}

This section needs expansion with: Real-life application/worked out eg. of Faraday's Laws. You can help by adding to it. (August 2020) |

## See also

## References

**^**Faraday, Michael (1834). "On Electrical Decomposition".*Philosophical Transactions of the Royal Society*.**124**: 77–122. doi:10.1098/rstl.1834.0008. S2CID 116224057.**^**Ehl, Rosemary Gene; Ihde, Aaron (1954). "Faraday's Electrochemical Laws and the Determination of Equivalent Weights".*Journal of Chemical Education*.**31**(May): 226–232. Bibcode:1954JChEd..31..226E. doi:10.1021/ed031p226.- ^
^{a}^{b}^{c}"Faraday's laws of electrolysis | chemistry".*Encyclopedia Britannica*. Retrieved 2020-09-01. **^**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

- Serway, Moses, and Moyer,
*Modern Physics*, third edition (2005), principles of physics. - Experiment with Faraday's laws