redoxsystem

Redoxsystem is a term used to describe a set of chemical species that can participate in oxidation–reduction (redox) reactions. In a redox system, electrons are transferred between species, causing changes in oxidation state. The system is defined by redox couples, which pair an oxidized form with a reduced form, and by the balance between oxidants and reductants that determines the direction of electron flow.

Redox potentials and electron transfer are central to a redox system. A species with a higher tendency to gain electrons has a more positive redox potential. When multiple couples are present, the overall feasibility of electron transfer is governed by the differences in their redox potentials. The Nernst equation relates the actual redox potential to the standard potential and the concentrations of the participating species. For a given couple, the standard redox potential, E°, provides a reference point. The change in Gibbs free energy for a redox process is ΔG° = -nFE°, where n is the number of electrons transferred and F is the Faraday constant.

Examples include inorganic couples such as Fe3+/Fe2+ and MnO4−/Mn2+, as well as biological cofactors such as NAD+/NADH and FAD/FADH2. In biology, redox systems are central to metabolism and energy transduction, as seen in electron transport chains and redox signaling pathways.

Applications span electrochemistry, batteries, corrosion, environmental redox chemistry, and biomedical contexts. Redox state and redox potential are routinely measured by potentiometric methods, redox titration, or cyclic voltammetry to assess reaction feasibility and system behavior.