Chapter 9

Oxidation-Reduction Reactions

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9.1 An Introduction to Oxidation-Reduction Reactions

9.2 Oxidation Numbers

9.3 Types of Chemical Reactions

9.4 Voltaic Cells

Review Skills

The presentation of information in this chapter assumes that you can already perform the tasks listed below. You can test your readiness to proceed by answering the Review Questions at the end of the chapter. This might also be a good time to read the Chapter Objectives, which precede the Review Questions.

Determine the charge on a monatomic ion in an ionic formula. (Section 5.3)

Determine the formulas, including the charges, for common polyatomic ions. (Section 6.1)

Identify a chemical formula as representing an element, a binary ionic compound, an ionic compound with one or two polyatomic ions, or a molecular compound. (Section 6.5)

n many important chemical reactions, electrons are transferred from atom to atom. We are surrounded by these reactions, commonly called oxidation-reduction (or redox) reactions, inside and out. Let’s consider a typical “new millennium” family, sitting around the dining room table after the dishes have been cleared.

Mom, a computer programmer, is typing away on her portable computer. She’s very anxious to see if the idea she got while on her drive home will fix a glitch in the accounting program at work. Christine, the thirteen-year-old, is fighting the bad guys on her video game. The electric currents from the batteries that power the computer and the game are generated by oxidation-reduction reactions. Buddy, who’s 15, has recently become interested in studying Eastern Philosophy. Just now, he’s gazing meditatively out into space, but redox reactions are powering his activity as well; they are important for the storage and release of energy in all our bodies. Dad’s an engineer in charge of blasting a tunnel under the bay for the city’s new rapid transit project. Each of the explosions that he triggers is created by oxidation-reduction reactions. The silverware he has just cleared from the table is tarnishing due to redox reactions, and the combustion of natural gas in the heater warming the room is a redox reaction as well…

Oxidation-reduction reactions power ourselves and many of our tools and toys.