Which of the following metals can offer cathodic protec-tion to iron? Select all the correct choices. Mn, Ni, Pb, Sn, Al
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Identify the concept of cathodic protection, which involves using a more reactive metal to prevent corrosion of a less reactive metal like iron.
Refer to the electrochemical series or standard reduction potential table to determine the reactivity of the given metals (Mn, Ni, Pb, Sn, Al) compared to iron.
Find the standard reduction potentials for each metal and compare them to the standard reduction potential of iron (Fe).
Select metals with a more negative standard reduction potential than iron, as these metals can act as sacrificial anodes and offer cathodic protection.
List the metals that have a more negative standard reduction potential than iron, indicating they can provide cathodic protection.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cathodic Protection
Cathodic protection is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. This is achieved by connecting the metal to a more reactive metal, which acts as a sacrificial anode. The more reactive metal oxidizes instead of the protected metal, thereby preventing corrosion.
The electrochemical series is a list of metals arranged according to their standard electrode potentials. Metals higher in the series are more reactive and can displace those lower in the series from their compounds. Understanding this series helps determine which metals can effectively provide cathodic protection to others, such as iron.
Galvanic corrosion occurs when two different metals are in electrical contact in the presence of an electrolyte, leading to the more reactive metal corroding preferentially. This principle is essential for cathodic protection, as selecting the right sacrificial anode can prevent the corrosion of the protected metal, like iron, by ensuring it remains the cathode in the electrochemical reaction.
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