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The term redox process accounts to all processes in which atoms have their oxidation number changed. This can be a simple redox process, such as the combustion of carbon by oxygen to yield carbon dioxide, it could be the reduction of carbon by hydrogen to yield methane, or it could be the oxidation of sugar in the human body, through a series of very complex electron transfer processes, to yield water and carbon dioxide.
The term redox comes from the two concepts of reduction and oxidation. Reduction descibes the uptake of an electron by a molecule or atom. Oxidation describes the loss of an electron by a molecule or atom. These two terms go together, because in a chemical reaction, one cannot occur without the other; electrons lost by one compound must be gained by another.
Substances having the capability to oxidize other substances are said to be oxidative and known as oxidizing agents/oxidants or oxidizers. Put in another way, the oxidant removes electrons from the substance. Oxidants are usually chemical substances in high oxidation numbers (eg. MnO4-, CrO3, OsO4) or very electronegative substances that can gain one or two extra electrons by oxidizing a substance (O2, O3, F2, Cl2, Br2)
Substances having the capability to reduce other substances are said to be reductive and known as reductive agents/reductants or reducers. Put in another way, the reductant transfers electrons to the substance. Reductants in chemistry are very diverse. Metal reduction - electropositive elemental metals can be used (Li, Na, Mg, Fe, Zn, Al). These metals are very eager to give away electrons. Other kinds of reductants are hydride transfer reagents (NaBH4, LiAlH4), these reagents are widely used in organic chemistry, primarily in the reduction of carbonyl compounds to alkohols. Another useful method is reductions involving hydrogen gas (H2) with a palladium, platinium or nickel catalyst. These catalytic reductions are primarily used in the reduction of carbon-carbon double or triple bonds.
The chemical way to look at redox processes is that the reductant transfers electrons to the oxidant. Thus, at the end of the reaction, the reductant will have become oxidized and the oxidant will have become reduced. This does not mean however, that the reverse process takes place (because that would lead to status quo), but it does often leads to equlibrium.
Formerly, oxidation (reduction) simply meant the addition (removing) of oxygen or the removing (addition) of hydrogen (hence the name oxidation). However, when the terms are now used it is normally in the more general sense.
A good example is the reaction between hydrogen and fluorine:
We can write this overall reaction as two half-reactions: an oxidation reaction:
and a reduction reaction:
Elements always have an oxidation number of zero. In the first half reaction hydrogen is oxidized from an oxidation number of zero to an oxidation number of +1. In the second half reaction fluorine is reduced from an oxidation number of zero to an oxidation number of −1.
When adding the reactions together the electrons cancel:
H2 → 2H+ +And the ions combine to form hydrogen fluoride:
2H+ + 2F- → 2HF
Here are some other examples:
iron(II) oxidises/oxidizes to iron(III):
overall equation for the above:
iron(II) oxidises/oxidizes to and oxygen reduces to iron(III) oxide (commonly known as rusting or tarnishing):
Another example is the burning of hydrocarbons to produce water, carbon dioxide, some partially oxidized forms, and heat energy. Complete oxidation of materials containing carbon produces carbon dioxide, which is linked to global warming because it absorbs certain wavelengthThe wavelength is the distance between repeating units of a wave pattern. It is commonly designated by the greek letter lambda (λ). In a sine wave, the wavelength is the distance between peaks: The x axis represents distance, and I would be some vas of infraredInfrared IR radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means "below red" (from the Latin infra "below"), red being the color of visible light of longest wavelength. light.
In organic chemistryOrganic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds. Organic nomenclature Organic nomenclature is the system established for naming and grouping organic compounds. Aliphatic co, stepwise oxidation of a hydrocarbon produces water and, successively, an alcoholIn general usage, alcohol (from Arabic al-khwl , or al-ghawl ) refers almost always to ethanol, also known as grain alcohol and often to any beverage that contains ethanol (see alcoholic beverage . This sense underlies the term alcoholism ( addiction to a, an aldehydeAn aldehyde is either a functional group consisting of a terminal carbonyl group, or a compound containing a terminal carbonyl group. Where -R represents the carbon chain. Structure The aldehyde functional group is a carbonyl group bonded to a hydrogen at or a ketoneA ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a compound that contains this functional group. A ketone can be generally represented by the formula: :R( C O)R. A carbonyl carbon bonded to two, carboxylic acidIn chemistry, carboxylic acids (also called alkanoic acids are organic acids characterized by the presence of a carboxyl group. Carboxylic acids thus have the structure : where R is a hydrogen or an organic group. In chemical formulas, this is also writte, and then a peroxide.
In inorganic chemistry terms, incompletely oxidized carbon takes the form of carbonate, bicarbonate or carbon monoxide.