Chapter 14

Redox Chemistry and Electrochemistry

Redox chemistry involves the study of reduction and oxidation reactions: Reduction refers to
reactions in which a species gains electrons, while oxidation refers to those in which a species gives
up or loses electrons. Since electrons can be neither created nor destroyed in normal chemical
reactions (as opposed to nuclear reactions, which will be discussed in the next chapter), an isolated
loss or gain of electrons cannot occur; in other words, neither oxidation nor reduction can occur all
by itself. Each occurs simultaneously in a redox reaction, resulting in net electron transfer between
the species. The electrons released during oxidation are taken up in the reduction process. The
species undergoing reduction is said to be reduced when it gains electrons; a reduced species is also
called an oxidizing agent because it causes something else (the species giving up the electrons) to
be oxidized. Similarly, a reducing agent causes another species to be reduced, and is itself oxidized.
This is summarized in Table 14.1 below:

Table 14.1 Properties   of  Oxidizing   and Reducing    Agents

Oxidizing   Agent Reducing  Agent

Gains   electrons Loses electrons

Also    known   as  a   reduced species Also    known   as  an  oxidized    species

Oxidation   number  decreases Oxidation number  increases

Oxidation   States  and Assigning   Oxidation   Numbers

Balancing   Redox   Reactions

Oxygen  as  an  Oxidizing   Agent   and the Chemistry   of  Oxides

Electrochemical Cells

Reduction   Potentials  and the Electromotive   Force

Thermodynamics  of  Redox   Reactions