Redox Reactions (Oxidation-Reduction)

Oxidation -  reduction reactions involve the transfer of electrons from an electron donor to an electron acceptor. This results in a change in the oxidation state of both the donor and acceptor. Any redox reaction can be broken down into two half-reactions, one reduction and one oxidation reaction. For example :

                                                Overall Reaction:                                             Fe+3 + Cu+ D    Fe+2 + Cu+2

                                                                Reduction:                                                               Fe+3 + e-  D Fe+2

                                                Oxidation:                                                               Cu+ D   Cu+2 + e-

 

The standard reduction potentials (E o') of commonly used half reactions can be found in the text (Table 16-4 on p. 573). These E o' values are measured physically by a voltmeter connected to an electrochemical cell, where the two half-reactions are placed in separate cells connected by a salt bridge which allows for ion transfer.  Each redox pair has an oxidizing agent (which itself gets reduced) and a reducing agent (which is oxidized).

 

These reactions help supply living organisms with most of their free energy. For example, in cells, the mitochondrial electron transfer chain utilizes NADH (an electron-transfer coenzyme) as an electron donor and several electron acceptors to pass electrons to O2. This reaction gets coupled to the formation of ATP from ADP and Pi.

 

For more information regarding redox reactions, you should look back to introductory Chemistry texts, or look for tutorials online. One which may be of interest to you for general information regarding the basics of redox reactions is linked below:

 

            Oxidation Numbers and Redox Reactions