Definition for oxidations

More generally, an oxidizer is any oxidizing agent. See definition for oxidation. 

As you will learn in this chapter, the modern definitions for oxidation and reduction are much broader. The current definitions are based on the idea of electron transfers, and can now be applied to numerous chemical reactions. In Unit 1, you saw the terms oxidation and reduction used to describe changes to carbon-hydrogen and carbon-oxygen bonds within organic compounds. These changes involve electron transfers, so the broader definitions that you will learn in this chapter still apply. 

Try using a mnemonic to remember the definitions for oxidation and reduction. For example, in "LEO the lion says GER," LEO stands for "Loss of Electrons is Oxidation." GER stands for "Gain of Electrons is Reduction." The mnemonic "OIL RIG" stands for "Oxidation Is Loss. Reduction Is Gain." Make up your own mnemonic to help you remember these definitions. 

The reaction of magnesium and oxygen is an example of an oxidation reaction. The combination of an element with oxygen was the traditional way to define an oxidation reaction. This definition of oxidation has been broadened by chemists to include reactions that do not involve oxygen. Our modern definition for oxidation is that oxidation takes place when a substance loses electrons. Anytime oxidation takes place and a substance loses one or more electrons, another substance must gain the electron(s). When a substance gains one or more electrons, the process is known as reduction. Reactions that involve the transfer of one or more electrons always involve both oxidation and reduction. These reactions are known as oxidation-reduction or redox reactions. 

One way to overcome this problem is to develop new definitions of oxidation and reduction that cover both the historical definitions in terms of oxygen and hydrogen and the modern definitions in terms of electrons. The concept of an oxidation number, which consists of a number and a sign, allows chemists to avoid the problems associated with using two separate and sometimes conflicting definitions for oxidation and reduction. 

During the reaction, a magnesium atom loses two electrons and an oxygen atom gains them. This gives us another definition for oxidation and reduction ... 

Inorganic membranes (29,36) are generaUy more stable than their polymeric counterparts. Mechanical property data have not been definitive for good comparisons. IndustriaUy, tube bundle and honeycomb constmctions predominate with surface areas 20 to 200 m. Cross-flow is generaUy the preferred mode of operation. Packing densities are greater than 1000 /m. Porous ceramics, sintered metal, and metal oxides on porous carbon support... 

For iridium the position is reversed. This time it is the black dioxide, Ir02, with the rutile structure (p. 961), which is the only definitely established oxide. It is obtained by heating the metal in oxygen or by dehydrating the precipitate produced when alkali is added to an aqueous solution of [IrCl6] . Contamination either by unreacted metal or by alkali is, however, difficult to avoid. The other oxide, Ir203, is said to be... 

For definiteness, the oxidation of copper to copper(l) oxide may be considered. Our picture of the process is that cation vacancies and positive holes formed at the Cu O/Oj interface by equation, 1.166 are transported to the Cu/CujO interface where they are destroyed by copper dissolving in the non-stoichiometric oxide. We require an expression for the rate of oxidation. 

Other ions which are reduced in the reductor to a definite lower oxidation state are those of titanium to Ti3+, chromium to Cr2+, molybdenum to Mo3+, niobium to Nb3+, and vanadium to V2 +. Uranium is reduced to a mixture of U3 + and U4+, but by bubbling a stream of air through the solution in the filter flask for a few minutes, the dirty dark-green colour changes to the bright apple-green colour characteristic of pure uranium(I V) salts. Tungsten is reduced, but not to any definite lower oxidation state. 

Earlier in this chapter, we learned definitions for the terms oxidation and reduction. We saw that oxidation involves an increase in oxidation state. For example, oxidation of a secondary alcohol will produce a ketone ... 

There is no room within the definition for nitric oxide, the prostaglandins and steroids mainly because they are not released in a controlled manner by neuronal activity and only the last are preformed. Thus if they are to be classified as NTs then the definition must be simplified so that a NT becomes ... 

Since Arrhenius, definitions have extended the scope of what we mean by acids and bases. These theories include the proton transfer definition of Bronsted-Lowry (Bronsted, 1923 Lowry, 1923a,b), the solvent system concept (Day Selbin, 1969), the Lux-Flood theory for oxide melts, the electron pair donor and acceptor definition of Lewis (1923, 1938) and the broad theory of Usanovich (1939). These theories are described in more detail below. 

It is also sometimes simply referred to as the gram-equivalent . However, GEW has two distinct definitions for neutralization as well as as oxidation-reduction reactions as stated below ... 

While the sequence of steps for the Heck reaction remains the same for many catalysts, the kinetics may vary enormously and also the detailed composition of all intermediates may vary in the type and number of ligands. It had often been assumed that the oxidative addition is the slowest step and that may well be true for many systems based on PPh3 definitely for aryl chlorides it seems to be the rule. 

With the preceding definitions, for the one-dimensional problem defined in Fig. 6.8, the expression for conservation of a species A (say the oxidizer) is... 

It has been argued that all steps in the reaction must be electrochemical in nature for the process to be called direct oxidation. According to this definition, any process that involves cracking of the hydrocarbon on the anode material, followed by electrochemical oxidation of the cracking products, should not be considered to be direct oxidation. The primary reason for using this narrow definition for direct oxidation is that the open-circuit voltage (OCV) of the cell will be equal to the theoretical, Nernst potential if there are no other losses and if all steps in the oxidation mechanism are electrochemical. 

The second definition of the purpose of a carrier was to remove the overburden of material above a surface above the device plane. For present purposes, we define the device level as the boundary between the material one wishes to remove and the material one wants to keep. It is not necessarily planar, and it moves up with each layer. For oxide CMP, this layer lies within the topmost film layer. For metal CMP, this surface is defined by the topmost surface of the dielectric into which lines and vias are etched for a damascene process. This definition must accommodate a wafer with a modest amount of bow, tilt, warp, and total thickness variation. Furthermore, it must accommodate very modest amounts of bow, warp, tilt. 

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