1. Module 3

1.19. Lesson 4

Lesson 4

Module 3—Electrochemical Reactions

Lesson 4—Oxidation Numbers and Corrosion Protection

 

Get Focused

 

A photograph shows links in a steel chain. The links appear dull grey in colour, except for the inside of each link where reddish-orange rust has developed. The rust is heaviest where the links in the chain connect.

© 2008 Jupiterimages Corporation

Throughout this module you have considered the reaction of metals with other substances. You have learned many techniques for interpreting the changes observed in chemical systems undergoing electrochemical change. You have also learned many new skills, namely the ability to predict the spontaneity of reactions and to explain disproportionation reactions.

 

Many structures rely on iron for their integrity. For example, reinforced concrete contains rods of steel, which is primarily composed of iron, called rebar. The frames of automobiles also rely on iron for their structural integrity. But we know iron can rust and, when it does, it loses its integrity. In the Module 3 Big Picture you read about the restoration of the High Level Bridge in Edmonton, Alberta, and the quantity of corroded material that was removed from the bridge. Since so many materials rely on iron or steel, corrosion has a great economic impact and presents serious safety concerns.

 

In Lesson 4 you will investigate the process of corrosion and how it can be further understood as a redox process. You will also learn about methods that are used to prevent the corrosion of iron.

 

Consider the following questions as you complete Lesson 4:

  • What are oxidation numbers and how can they be used to understand redox reactions?
  • What factors cause corrosion?
  • How can corrosion be prevented?
Module 3: Lesson 4 Assignment

 

Download a copy of the Module 3: Lesson 4 Assignment to your computer now. You will receive further instructions on how to complete this assignment later in the lesson. The assignment has the following three parts:

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

You must decide what to do with the questions that are not marked by the teacher.

 

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should respond to all the questions and place those answers in your course folder.