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.

Verified step by step guidance

1. Understand the concept of cathodic protection: It is a technique used to prevent corrosion of a metal surface by making it the cathode of an electrochemical cell.
2. Identify the role of a sacrificial anode: In cathodic protection, a more easily oxidized metal (sacrificial anode) is used to protect the metal of interest (cathode).
3. Analyze the options: Determine which option involves using a more easily oxidized metal to protect steel.
4. Option (c) involves coating steel with zinc, which is more easily oxidized than iron, providing cathodic protection.
5. Option (d) involves attaching a strip of magnesium to steel, where magnesium is more easily oxidized than iron, also providing cathodic protection.

Key Concepts

Cathodic Protection

Cathodic protection is a technique used to prevent corrosion of metal surfaces, particularly in structures like pipelines and ships. It involves making the metal surface the cathode of an electrochemical cell, which reduces the oxidation process that leads to corrosion. This can be achieved through sacrificial anodes or impressed current systems.

Sacrificial Anodes

Sacrificial anodes are metals that are more reactive than the metal they are protecting, such as zinc or magnesium. When attached to a structure like steel, these anodes corrode preferentially, thereby protecting the steel from oxidation. This method is commonly used in marine applications and underground pipelines.

Oxidation and Reduction

Oxidation and reduction are chemical processes that involve the transfer of electrons between substances. Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons. In the context of cathodic protection, the metal being protected (like iron in steel) is reduced, preventing it from oxidizing and corroding.