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Ch.20 - Electrochemistry
Chapter 20, Problem 91c

Determine whether or not each metal, if coated onto iron, would prevent the corrosion of iron. c. Mn

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Understand the concept of galvanic corrosion: When two different metals are in contact in the presence of an electrolyte, the more reactive metal (anode) will corrode preferentially, protecting the less reactive metal (cathode).
Identify the position of manganese (Mn) and iron (Fe) in the electrochemical series or activity series of metals. The series ranks metals by their tendency to lose electrons (oxidize).
Compare the reactivity of Mn and Fe: If Mn is more reactive than Fe, it will act as the anode and corrode first, protecting the iron. If Mn is less reactive, it will not protect the iron.
Check the standard electrode potentials: Mn has a more negative standard electrode potential than Fe, indicating it is more reactive and will oxidize preferentially.
Conclude that Mn, being more reactive, will corrode first if coated onto iron, thus preventing the corrosion of iron by acting as a sacrificial anode.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Corrosion

Corrosion is the process by which metals deteriorate due to chemical reactions with their environment, often involving oxidation. In the case of iron, it typically forms rust (iron oxide) when exposed to moisture and oxygen. Understanding corrosion is essential to evaluate how different metals can protect iron from this degradation.
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Galvanic Series

The galvanic series is a list of metals arranged according to their electrochemical potential in a specific environment, which helps predict their behavior in corrosion processes. Metals higher in the series are more noble and less likely to corrode, while those lower are more reactive. This concept is crucial for determining whether a metal coating can effectively protect iron from corrosion.
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Sacrificial Anode

A sacrificial anode is a metal that is intentionally corroded to protect another metal, such as iron, from corrosion. When a less noble metal is used as a coating, it will corrode preferentially, thereby protecting the underlying iron. This principle is often applied in corrosion prevention strategies, making it vital for assessing the effectiveness of different metal coatings.
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