Oxidation-reduction

Oxidation-reduction (also known as redox) is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron. Redox reactions are common and vital to some of the basic functions of life, including photosynthesis, respiration, combustion, and corrosion or rusting.

Overview

The term "redox" comes from two concepts involved with electron transfer: "reduction" and "oxidation". Reduction refers to the gain of electrons by a molecule, atom, or ion. Conversely, oxidation is the loss of electrons from a molecule, atom, or ion. Because the ability of an entity to gain electrons corresponds with its ability to reduce other entities, and vice versa, these two concepts are often studied together as redox reactions.

Redox reactions in biology

Redox reactions play a key role in biological processes. For example, in cellular respiration, organisms convert energy from glucose into ATP (adenosine triphosphate), the "energy currency" of cells. This process involves the oxidation of glucose and the reduction of oxygen. Similarly, in photosynthesis, plants convert carbon dioxide and water into glucose and oxygen. This process involves the reduction of carbon dioxide and the oxidation of water.

Redox reactions in chemistry

In chemistry, redox reactions are often involved in corrosion, combustion, and reactions that produce electricity in batteries. For example, in the reaction between hydrogen and fluorine, the hydrogen is oxidized whereas the fluorine is reduced.

Balancing redox reactions

Balancing redox reactions can be complex. The half-reaction method is often used. This involves separating the oxidation and reduction of a redox pair into two separate half-reactions.

See also

• Electrochemistry
• Oxidizing agent
• Reducing agent
• Redox potential
• Redox signaling

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