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Ch.19 - Electrochemistry
Chapter 19, Problem 130

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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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.
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Electrochemical Series

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.
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Galvanic Corrosion

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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Related Practice
Textbook Question
Which of the following describes the process of galvanization that protects steel from rusting? (a) Steel is coated with a layer of paint. (b) Iron in steel is oxidized to form a protective oxide coating. (c) Steel is coated with zinc because zinc is more easily oxidized than iron. (d) A strip of magnesium is attached to steel because the magnesium is more easily oxidized than iron.
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Textbook Question
What is meant by cathodic protection? (a) Steel is coated with a layer of paint. (b) Iron in steel is oxidized to form a protective oxide coating. (c) Steel is coated with zinc because zinc is more easily oxidized than iron. (d) A strip of magnesium is attached to steel because the magnesium is more easily oxidized than iron.
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Textbook Question

Zinc is attached to a ship's steel propeller to prevent the steel from rusting. Write balanced equations for the corro-sion reactions that occur (a) in the presence of Zn and (b) in the absence of Zn.

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Textbook Question
Magnesium metal is produced by the electrolysis of molten magnesium chloride using inert electrodes. (a) Sketch the cell, label the anode and cathode, indicate the sign of the electrodes, and show the direction of electron and ion flow.
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Textbook Question
(a) Sketch a cell with inert electrodes suitable for the elec-trolysis of an aqueous solution of sulfuric acid. Label the anode and cathode, and indicate the direction of electron and ion flow. Identify the positive and negative electrodes. (b) Write balanced equations for the anode, cathode, and overall cell reactions.
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Textbook Question
What products should be formed when the following reac-tants are electrolyzed in a cell having inert electrodes? Account for any differences. (b) Aqueous KCl
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