redoks

Redoks, short for reduction-oxidation, refers to chemical reactions in which electrons are transferred between species. In a redoks reaction, one substance is oxidized, losing electrons, while another is reduced, gaining electrons. The substance that is oxidized acts as the reducing agent; the substance that is reduced acts as the oxidizing agent. The process is accompanied by changes in oxidation states of atoms, and often by color changes or energy release. Redox couples are the two half-reactions representing the oxidation and reduction processes.

The driving force of redox reactions is the difference in redox potential. Standard redox potential (E°) indicates a species’ tendency to gain electrons under standard conditions. The Nernst equation relates E to the actual concentrations, temperature, and pH, allowing calculation of cell potentials and reaction direction under nonstandard conditions.

In biological systems, redox reactions underpin metabolism and energy production. Carriers such as NAD+/NADH and FAD/FADH2 transport electrons to the mitochondrial electron transport chain, contributing to ATP synthesis. In environmental chemistry, redox conditions influence the speciation and mobility of elements, affecting processes like iron and manganese cycling, sulfate reduction, and arsenic behavior.

Industrial and analytical chemistry use redox reactions for synthesis, disinfection, and various forms of analysis. Redox titrations employ reagents such as potassium permanganate, dichromate, or iodate to determine amounts of oxidizable or reducible substances. Measurements often rely on potentiometry, voltammetry, or spectroelectrochemistry.

Redoks processes can be exothermic and require appropriate handling and safeguards.