Redox reactions, short for reduction-oxidation reactions, are chemical processes in which the oxidation state of one or more substances changes. These reactions involve the transfer of electrons between two species, resulting in the reduction of one substance and the oxidation of another.
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Oxidation is the process where a substance loses electrons, leading to an increase in its oxidation state. For example, when iron (Fe) oxidizes to form iron (III) ions (Fe³⁺), it loses electrons.
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Reduction is the process where a substance gains electrons, resulting in a decrease in its oxidation state. For instance, when copper (II) ions (Cu²⁺) gain electrons to form elemental copper (Cu), they are reduced.
In a redox reaction, the substance that donates electrons (is oxidized) is called the reducing agent, while the substance that accepts electrons (is reduced) is called the oxidizing agent. Redox reactions are fundamental to many biological processes, electrochemical cells, and various industrial applications.
Overall, the essential characteristic of redox reactions is the coupling of oxidation and reduction processes, where one cannot occur without the other. The general representation of a redox reaction can be summarized by the equation:
\[ \text{Oxidation: } A \rightarrow A^n+ + ne^- \]
\[ \text{Reduction: } B + ne^- \rightarrow B^m \]
In this context, \( A \) is oxidized, \( B \) is reduced, and \( n \) represents the number of electrons transferred.