Britannica
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- oxidation-reduction reaction
- oxidation-reduction reaction - Half reactions
- oxidation-reduction reaction - Oxidation-state change
- oxidation-reduction reaction - Examples of oxidation-reduction reactions
- oxidation-reduction reaction - Mechanisms of redox reactions
- chemical reaction - Oxidation-reduction reactions
How do oxidation-reduction reactions transfer electrons between substances?
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chemical reaction
Log burning in a fire. Burning wood is an example of a chemical reaction in which wood in the presence of heat and oxygen is transformed into carbon dioxide, water vapor, and ash.
In oxidation-reduction (redox) reactions, electrons are transferred from a reducing agent to an oxidizing agent. This transfer results in a change in the oxidation number of the participating atoms: the substance that loses electrons is oxidized (its oxidation number increases), while the substance that gains electrons is reduced (its oxidation number decreases).12
This process can occur through several mechanisms:
- Direct Electron Transfer: In many cases, particularly with metal ions in solution, electrons move directly between species. This principle is utilized in electrochemical cells, where electrons flow through an external wire between separate compartments, generating an electric current.341
- Atom Transfer: Redox reactions can also be facilitated by the transfer of oxygen or hydrogen atoms. In these instances, the electron transfer is often implicit in the change of bonding patterns.2
- Bridging Mechanisms: When metal ions react, they may form an intermediate where they share a common bridging group (such as a hydroxide ion). In these inner-sphere reactions, the bridge acts as a pathway for the electrons to move from one metal to the other.5