If the current generated by one of the anodic reactions expressed earlier was known, it would be possible to convert this current to an equivalent mass loss or corrosion penetration rate with a very useful relation discovered by Michael Faraday, a nineteen century pioneer in electrochemistry. Faraday

According to **Faraday’s law**, the reaction with one mole of silver would require one mole of electrons, or one **Avogadro****6.022 x 10**^{23}). The charge carried by one mole of electrons is known as one Faraday (F). **The Faraday** is related to other electrical units through the electronic charge, i.e electron charge is **1.6 x 10**^{-19}** coulomb**. Multiplying the electronic charge by the Avogadro number means that one Faraday equals **96,485 C/(mole of electrons)**. Combining Faraday’s principles with specific electrochemical reactions of known stoichiometry leads to equation:

where:

where **N** is the number of moles and DN the change in that amount

**n** is the number of electrons per molecule of the species being reacted

**I **is the total current in amperes (A)

**t** is the duration of the electrochemical process in seconds (s)

24 g of zinc metal are dissolved in a 1 M HCl solution. How many coulombs have been produced by the anodic process?

The
corrosion current itself can be either estimated by using specialized electrochemical methods or by using weight loss data and a ** conversion chart based on Faraday’s principle**.

A sheet of carbon steel one meter wide by three meter
long has lost 40 g to corrosion over the past six months. Convert that mass
loss to a penetration rate of the steel in mm units. What would be the total
corrosion current associated with such a corrosion rate? (carbon steel
density = 7.8 g/cm^{3})

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