Oxidation-reduction reactions redox

Equilibrium considerations other than those of binding are those of oxidation/reduction potentials to which we drew attention in Section 1.14 considering the elements in the sea. Inside cells certain oxidation/reductions also equilibrate rapidly, especially those of transition metal ions with thiols and -S-S- bonds, while most non-metal oxidation/reduction changes between C/H/N/O compounds are slow and kinetically controlled (see Chapter 2). In the case of fast redox reactions oxidation/reduction potentials are fixed constants. 

Oxidation—Reduction. Redox or oxidation—reduction reactions are often governed by the hard—soft base rule. For example, a metal in a low oxidation state (relatively soft) can be oxidized more easily if surrounded by hard ligands or a hard solvent. Metals tend toward hard-acid behavior on oxidation. Redox rates are often limited by substitution rates of the reactant so that direct electron transfer can occur (16). If substitution is very slow, an outer sphere or tunneling reaction may occur. One-electron transfers are normally favored over multielectron processes, especially when three or more species must aggregate prior to reaction. However, oxidative addition... 

The ability to balance a single half-reaction as a bookkeeping exercise does not mean that a single half-reaction can occur on its own. In a redox reaction, oxidation and reduction must both occur. 

The Daniell cell illustrates the basic features of an electrochemical cell. Electrochemical cells always involve a redox reaction. Oxidation occurs at the cathode of the cell and reduction takes place at the anode. Electrons always flow from the anode to the cathode. Electrochemical cells come in many arrangements. To gain an appreciation for the variety of electrochemical cells, consider all the types of batteries available. 

Today, many reactions in aqueous solutions can be described as oxidation-reduction reactions (redox reactions). Oxidation is the process in which the oxidation number of atoms increases. Reduction is the process in which the oxidation number of atoms is decreased or made more negative. In another definition, oxidation is the loss of electrons by an atom, and reduction is the gain of electrons. Let us look at the following reaction ... 

In redox reactions, oxidation and reduction processes occur at the same time. The following reaction is an oxidation-reduction reaction. For example,... 

The consequences are obvious. The redox reaction with reduction of D has at equilibrium a much lower Fermi energy, that means a more positive redox potential, the redox reaction with oxidation of D has a much higher Fermi energy, that is a more negative redox potential than in the ground state. This is schematically demonstrated in Fig. 1. 

A reaction in which the oxidation number of an element is increased. Examples (1, 2, 3) 2 Mg(s) + 02(g) - 2 MgO(s) (2, 3) Mg(s) - Mg2+(s) + 2e". oxidation number The effective charge on an atom in a compound, calculated according to a set of rules (Toolbox K.l). An increase in oxidation number corresponds to oxidation, and a decrease, to reduction, oxidation-reduction reaction See redox reaction. oxidation state The actual condition of a species with a specified oxidation number. 

Any time electrons are transferred between reactants in a chemical reaction, the reaction is called an oxidation-reduction reaction. Oxidation-reduction reactions are also called redox reactions. 

In a redox reaction, oxidation and reduction occur at the same time. 

Complete the concept map using the following terms decreases, half-reactions, gain electrons, reduction, lose electrons, redox reaction, oxidation, increases. 

Are these reactions oxidation-reduction reactions Are electrons transferred Simply reading a chemical equation does not always tell us whether oxidation and reduction have occurred, so chemists have developed a numerical system to help identify a reaction as redox. For redox reactions, this system also shows us which element is oxidized, which is reduced, what the oxidizing agent is, and what the reducing agent is. 

Since these are ionic compounds and, therefore, redox species (Table IV), the expert system will check for redox reactions, using reduction potentials for each combination of component elements from the two reactants to decide whether any redox will occur. Iron(III) will oxidize chromium(II in this system. 

Whereas acid-base reactions can be characterized as proton-transfer processes, the class of reactions called oxidation-reduction, or redox, reactions are considered electron-transfer reactions. Oxidation-reduction reactions are very much a part of the world around ns. They range from the burning of fossil fuels to the action of household bleach. Additionally, most metallic and nomnetaUic elements are obtained from their ores by the process of oxidation or reduction. 

In redox reactions, oxidation and reduction always occur simultaneously. Oxidation is characterized by the loss of electrons, reduction by the gain of electrons. 

Reactions like this one, in which one or more electrons are transferred, are called oxidation-reduction reactions, or redox reactions. Oxidation is... 

An intriguing variation of this model involves the cellular chemistry of Cu(ii)(2,9-dimethyl-l,10-phenanthroline)2 [Cu(NC)2]. Cu(Phen)2 readily catalyzes the redox reaction of reductants with O2, because Cu(i)(Phen)2 is an unstable oxidation state in the presence of O2. In contrast, Cu(NC)2 does not catalyze these reactions when a noncoordinating reductant such as ascorbate is... 

Electrochemistry is ranked by teachers and students as one of the most difficult curriculum domains taught and learnt in secondary school chemistry (cf. Davies, 1991 Griffiths, 1994). For that reason, in this chapter, we primarily discuss this domain at the secondary level but also make connections to the tertiary level. In many chemistry curricula and textbooks, it is common to divide electrochemistry into two topics redox reactions (oxidation and reduction) and electrochemical cells (galvanic and electrolytic). The usual rationale for this distinction is that students need an understanding of oxidation-reduction to apply it to electrochemical cells. This analytical distinction, based on differences in the location of the half reactions, is used throughout the chapter. 

Intensity is the ease of rednction nsnally represented by the free energy of reduction or by the equivalent EMF of the reactions—oxidation-reduction potential or redox potential. 

Redox Reactions Oxidative Addition and Reductive Elimination... 

Reactions like this one, in which one or more electrons are transferred, are called oxidation-reduction reactions, or redox reactions. Oxidation is defined as a loss of electrons. Reduction is defined as a gain of electrons. In the reaction of elemental sodium and chlorine, each sodium atom loses one electron, forming a l-i- ion. Therefore, sodium is oxidized. Each... 

Redox Reactions Oxidation and reduction processes which affects the stability and persistence of electron acceptors (e.g., oxygen, ferric iron, nittate, etc.) and donors (e.g., organic matter, ferrous iron, sulfide, etc.) often mediated by microbial activity. 

In any electrochemical system, there are two electrodes, an anode and a cathode. During electrolysis, electrons are consumed at the cathode while they are generated at the anode. The reactions occurring at the individual electrodes are usually called the component electrochemical reactions, the combination being termed a redox, or oxidation-reduction, reaction system. Let us now examine the component electrochemical reactions involved in the overall reaction. 

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