How iron can be prevented from rusting?

Connecting iron to more electropositive metal, cathodic protection.

The correct answer is option 1. Connecting iron to more electropositive metal, cathodic protection.

Iron can be prevented from rusting using several techniques, and one of the effective methods is cathodic protection. Let’s explore the options:

Cathodic Protection

Method: This involves connecting the iron to a more electropositive metal, which acts as a sacrificial anode.

Explanation: In this setup, the more electropositive metal (such as zinc or magnesium) corrodes preferentially, protecting the iron from rusting. The iron becomes the cathode in this electrochemical cell, and the more electropositive metal (sacrificial anode) corrodes instead.

Usage: Commonly used in galvanization where zinc is coated on iron or steel to prevent rusting.

Anodic Protection

Method: This involves connecting iron to a less electropositive metal, which makes the iron the anode.

Explanation: The iron (which becomes the anode) would then corrode preferentially. This is not a protective measure but rather a technique that could accelerate corrosion if not managed properly.

Summary of Options:

1. Connecting iron to more electropositive metal, cathodic protection: This is correct and effectively prevents rusting by making the iron the cathode and the more electropositive metal the sacrificial anode.

2. Connecting iron to more electropositive metal, anodic protection: This is incorrect for preventing rusting as it would not protect iron but rather promote its corrosion.

3. Connecting iron to less electropositive metal, anodic protection: This is incorrect because it would lead to the iron corroding rather than being protected.

4. Connecting iron to less electropositive metal, cathodic protection: This is incorrect because it would not effectively prevent rusting. The iron should be connected to a more electropositive metal for effective cathodic protection.

Correct Answer: Connecting iron to more electropositive metal, cathodic protection.