Module 3

Module 3—Electrochemical Reactions

Reflect and Connect

Billions of dollars are spent every year to prevent or slow the corrosion of iron. The following are some methods to prevent the corrosion of iron.

1. Mix metals with iron to form a more corrosion-resistant alloy. Alloys have a unique set of properties. Stainless steel is an iron alloy. It contains mostly iron, between 10% to 30% chromium, a smaller percentage of nickel, and sometimes cobalt.
   
   
2. Paint exposed iron surfaces. Applying a coating prevents water and oxygen from gaining access to iron and therefore prevents oxidation of the iron.
   
   
3. Plate iron with another metal. Like paint, the layer of other metal prevents water and oxygen from gaining access to iron. Chromium and zinc (galvanization) are commonly used for plating iron. You will learn more about electroplating in the next module.
   
   
4. Apply oils and grease to exposed iron. This method is often used on the moving parts of machinery. Oils and grease repel water because of the lack of polarity in the molecules.

You will address a corrosion problem in the Module 3 Assessment. You might want to view the Module 3 Assessment now and consider which of the four methods listed above might be applied to the corrosion problem. You may wish to record any ideas you have so that you can revisit them after you have completed all the lessons in this module and are ready to complete the Module 3 Assessment.

You will learn more about other methods to protect iron from corrosion in Module 4.

Module 3: Lesson 4 Assignment

Retrieve your copy of Module 3: Lesson 4 Assignment that you saved to your computer earlier in this lesson. Complete Part 3: Questions. Save your work in your course folder.

Make sure you have completed all parts of the Assignment:

• Part 1: Lab—Oxidation States of Manganese
• Part 2: Lab—Corrosion of Nails
• Part 3: Questions

Submit your completed Module 3: Lesson 4 Assignment to your teacher.

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