Redox

Redox (/ˈrɛdɒks/ RED-oks, /ˈriːdɒks/ REE-doks, reduction–oxidation[2] or oxidation–reduction[3]: 150 ) is a type of chemical reaction in which the oxidation states of the reactants change.

[5] In electrochemical reactions the oxidation and reduction processes do occur simultaneously but are separated in space.

Later, the term was expanded to encompass substances that accomplished chemical reactions similar to those of oxygen.

Ultimately, the meaning was generalized to include all processes involving the loss of electrons or the increase in the oxidation state of a chemical species.

Electropositive elemental metals, such as lithium, sodium, magnesium, iron, zinc, and aluminium, are good reducing agents.

[3]: 288 The electrochemist John Bockris proposed the words electronation and de-electronation to describe reduction and oxidation processes, respectively, when they occur at electrodes.

[17] They have not been widely adopted by chemists worldwide,[citation needed] although IUPAC has recognized the terms electronation[18] and de-electronation.

[19] Redox reactions can occur slowly, as in the formation of rust, or rapidly, as in the case of burning fuel.

[20] The mechanisms of atom-transfer reactions are highly variable because many kinds of atoms can be transferred.

[citation needed] Redox reactions are the foundation of electrochemical cells, which can generate electrical energy or support electrosynthesis.

The process of electroplating uses redox reactions to coat objects with a thin layer of a material, as in chrome-plated automotive parts, silver plating cutlery, galvanization and gold-plated jewelry.

Photosynthesis involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen.

The reverse reaction, respiration, oxidizes sugars to produce carbon dioxide and water.

As intermediate steps, the reduced carbon compounds are used to reduce nicotinamide adenine dinucleotide (NAD+) to NADH, which then contributes to the creation of a proton gradient, which drives the synthesis of adenosine triphosphate (ATP) and is maintained by the reduction of oxygen.

The term redox state is often used to describe the balance of GSH/GSSG, NAD+/NADH and NADP+/NADPH in a biological system such as a cell or organ.

The redox state is reflected in the balance of several sets of metabolites (e.g., lactate and pyruvate, beta-hydroxybutyrate and acetoacetate), whose interconversion is dependent on these ratios.

Once formed, these anion free radicals reduce molecular oxygen to superoxide and regenerate the unchanged parent compound.

The net reaction is the oxidation of the flavoenzyme's coenzymes and the reduction of molecular oxygen to form superoxide.

The main chemical reaction producing the molten iron is:[26] Electron transfer reactions are central to myriad processes and properties in soils, and redox potential, quantified as Eh (platinum electrode potential (voltage) relative to the standard hydrogen electrode) or pe (analogous to pH as -log electron activity), is a master variable, along with pH, that controls and is governed by chemical reactions and biological processes.

[27] Later work built on this foundation, and expanded it for understanding redox reactions related to heavy metal oxidation state changes, pedogenesis and morphology, organic compound degradation and formation, free radical chemistry, wetland delineation, soil remediation, and various methodological approaches for characterizing the redox status of soils.