Oxidation-Reduction Reactions
Definition and meaning of Oxidation-Reduction Reactions in chemistry.
Oxidation-reduction reactions (redox reactions) are chemical reactions in which electrons are transferred from one substance to another. One reactant is oxidized (loses electrons) while another is reduced (gains electrons), always occurring together.
In more detail
In a redox reaction, the substance losing electrons is called the reducing agent, and the substance gaining electrons is called the oxidizing agent. Oxidation state changes indicate whether electron transfer has occurred. These reactions are fundamental to many important processes, including combustion, corrosion, photosynthesis, cellular respiration, and battery operation, and are essential in nature and technology. Historically, oxidation was thought to refer only to combination with oxygen, but the modern definition emphasizes electron transfer regardless of whether oxygen is actually present.
Key facts
| Oxidation | Loss of electrons; oxidation state increases |
|---|---|
| Reduction | Gain of electrons; oxidation state decreases |
| Key Process | Electron transfer between an oxidizing and reducing agent |
| Field | General Chemistry |
When copper metal is placed in a solution of silver nitrate, copper is oxidized (loses electrons) and silver ions are reduced (gain electrons), forming copper(II) nitrate and silver metal: Cu + 2AgNO3 → Cu(NO3)2 + 2Ag.
Frequently asked questions
What's the difference between oxidation and reduction?
Oxidation is the loss of electrons (increase in oxidation state), while reduction is the gain of electrons (decrease in oxidation state). They always occur together in a redox reaction.
Does oxidation always involve oxygen?
No. Although oxidation historically meant combination with oxygen, modern redox chemistry defines oxidation as any loss of electrons, which can occur without oxygen.