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Ch.19 - Electrochemistry
Chapter 19, Problem 88b

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

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1
Step 1: Understand the concept of corrosion. Corrosion is an electrochemical process that involves the oxidation of a metal, in this case, iron. The metal that corrodes acts as the anode in the electrochemical cell, where oxidation (loss of electrons) occurs.
Step 2: Recognize that for a metal to prevent the corrosion of iron, it must be more easily oxidized than iron. This is because the more easily oxidized metal will act as the anode instead of the iron, thus preventing the iron from corroding.
Step 3: Consult the electrochemical series or standard reduction potentials table. This table lists metals in order of their ease of oxidation. Metals at the top of the table are more easily oxidized than those at the bottom.
Step 4: Compare the positions of chromium (Cr) and iron (Fe) in the table. If chromium is above iron in the table, it will be more easily oxidized and thus can prevent the corrosion of iron.
Step 5: Make a conclusion based on the comparison. If chromium is indeed more easily oxidized than iron, it can be used to coat iron to prevent its corrosion. If not, it won't be effective in preventing corrosion.

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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 determine how different metals can protect iron from this degradation.
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Galvanic Protection

Galvanic protection is a method of preventing corrosion by using a more reactive metal to protect a less reactive one. When a more anodic metal is coated onto iron, it can corrode preferentially, thus sacrificing itself to protect the iron beneath. This principle is crucial in evaluating whether a metal like chromium (Cr) can effectively prevent iron corrosion.
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Electrochemical Series

The electrochemical series is a list of metals arranged by their standard electrode potentials, indicating their tendency to be oxidized or reduced. Metals higher in the series are more reactive and can displace those lower in the series from their compounds. This concept helps in predicting whether a metal coating will protect iron from corrosion based on its position in the series relative to iron.
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