One important type of chemical reaction is the oxidation-reduction reaction, also known as the redox reaction. Although we introduced redox reactions in Section 4.7, it is worth reviewing some basic concepts.
- 14.1: Introduction to Oxidation and Reduction
- Most of us are familiar with rusty iron: metal that has a dark red-brown scale that falls off an object, ultimately weakening it. Although we usually attribute rusting exclusively to iron, this process occurs with many materials. The more formal term for rusting is corrosion. Corrosion is an example of the type of chemical reaction discussed in this chapter. Although we usually think of corrosion as bad, the reaction it typifies can actually be put to good use.
- 14.2: Oxidation-Reduction Reactions
- Oxidation-reduction (redox) reactions involve the transfer of electrons from one atom to another. Oxidation numbers are used to keep track of electrons in atoms. There are rules for assigning oxidation numbers to atoms. Oxidation is an increase in oxidation number (loss of electrons); reduction is a decrease in oxidation number (gain of electrons).
- 14.3: Balancing Redox Reactions
- Redox reactions can be balanced by inspection or by the half reaction method. A solvent may participate in redox reactions; in aqueous solutions, H2O, H+, and OH− may be reactants or products.
- 14.4: Applications of Redox Reactions - Voltaic Cells
- A voltaic cell produces electricity as a redox reaction occurs. The voltage of a voltaic cell can be determined by the reduction potentials of the half reactions. Voltaic cells are fashioned into batteries, which are a convenient source of electricity.
- 14.5: Electrolysis
- Electrolysis is the forcing of a nonspontaneous redox reaction to occur by the introduction of electricity into a cell from an outside source. Electrolysis is used to isolate elements and electroplate objects.
Thumbnail: Copper from a wire is displaced by silver in a silver nitrate solution it is dipped into, and solid silver precipitates out. Image used with permission (CC SA-BY 3.0 au; Toby Hudson).