Equation oxidation-reduction reactions

We can now apply our knowledge of partial ionic equations to the subject of equivalents. The standard oxidation-reduction process is H H+ + e, where e represents an electron per atom, or the Avogadro number of electrons per mole. If we know the change in the number of electrons per ion in any oxidation-reduction reaction, the equivalent may be calculated. The equivalent of an oxidant or a reductant is the mole divided by the number of electrons which 1 mole of the substance gains or loses in the reaction, e.g. ... 

In Sec. 13.2 we will learn to determine oxidation numbers from the formulas of compounds and ions. We will learn how to assign oxidation numbers from electron dot diagrams and more quickly from a short set of rules. We use these oxidation numbers for naming the compounds or ions (Chap. 6 and Sec. 13.4) and to balance equations for oxidation-reduction reactions (Sec. 13.5). In Sec. 13.3 we will learn to predict oxidation numbers for the elements from their positions in the periodic table in order to be able to predict formulas for their compounds and ions. 

Determining the net ionic equation by balancing the oxidation-reduction reaction skeletal equation Cu(s) + HN03(ag) - Cu2+(aq) + NO(g)... 

From the above equations, it is seen that the value of K is related to the value of AG° and E° of the cell, but not AG and E of the cell. E°, AG° and K are indicators of the thermodynamic tendency of an oxidation-reduction reaction to occur under standard conditions. 

Harry B. Gray and Walther Ellis,13 writing in Chapter 6 of reference 13, describe three types of oxidation-reduction centers found in biological systems. The first of these, protein side chains, may undergo oxidation-reduction reactions such as the transformation of two cysteine residues to form the cystine dimer as shown in equation 1.28 ... 

The usefulness of determining the oxidation number in analytical chemistry is twofold. First, it will help determine if there was a change in oxidation number of a given element in a reaction. This always signals the occurrence of an oxidation-reduction reaction. Thus, it helps tell us whether a reaction is a redox reaction or some other reaction. Second, it will lead to the determination of the number of electrons involved, which will aid in balancing the equation. These latter points will be discussed in later sections. 

In this chapter, you will be introduced to oxidation-reduction reactions, also called redox reactions. You will discover how to identify this type of reaction. You will also find out how to balance equations for a redox reaction. 

Many metals are also vulnerable to acids, undergoing an oxidation /reduction reaction that produces the metal ion and hydrogen gas. The balanced equation for the reaction between HCl and magnesium is... 

Here n represents the number of electrons transferred in the reaction. With this equation we can calculate the free-energy change for any oxidation-reduction reaction from the values of E" in a table of reduction potentials (Table 13-7) and the concentrations of the species participating in the reaction. 

We can now construct a balance sheet for glycolysis to account for (1) the fate of the carbon skeleton of glucose, (2) the input of P, and ADP and the output of ATP, and (3) the pathway of electrons in the oxidation-reduction reactions. The left-hand side of the following equation shows all the inputs of ATP, NAD+, ADP, and Pj (consult Fig. 14-2), and the right-hand side shows all the outputs (keep in mind that each molecule of glucose yields two molecules of pyruvate) ... 

An oxidation-reduction reaction occurs when sodium and chlorine react to form sodium chloride, as shown in Figure 11.1. The equation for this reaction is... 

Half-reaction One portion of an oxidation-reduction reaction, represented by an equation showing electrons as either reactants or products. 

Whether a reversible oxidation-reduction reaction involves a transfer of oxygen, hydrogen, both, or neither, there is a transfer of electrons between atoms or molecules. Reduction is the addition of electrons and oxidation is the withdrawal of electrons from a molecule. On this basis, and the law of mass action, the following basic equation can be derived (Clark 1960) ... 

The mechanism of an oxidation-reduction reaction can be simple, as illustrated by the ferrocene-ferricenium self-exchange in equation (1) where only electron transfer need occur.1 In other cases the mechanistic demands imposed by the net reaction are far greater. An example is shown in reaction (2) where, in the net sense, two protons and two electrons must be transferred from isopropanol, which is the reducing agent, to the RuIV oxidizing agent.2... 

B 8. The breakdown of hydrogen peroxide catalyzed by peroxidase is an oxidation-reduction reaction. Study Equation E12.1 and answer the following questions. 

How does the anionic alkyl of the original trialkylaluminum or of the dialkylaiuminum chloride, which has sufficient anionic character to undergo anionic hydride exchange or CH3OT reaction, form a catalyst which becomes cationic under certain polymerization conditions No studies of this have been reported. One possibility is an internal oxidation-reduction reaction that converts an anionic alkyltitanium trichloride to a cationic alkyltitanium trichloride (Equation 10). Basic and electrophilic catalyst components would determine the relative contributions of the anionic and cationic forms. This type of equilibrium or resonance structures could also explain the color in transition metal compounds such as methyltitanium trichloride (73). 

The reaction between sodium metal and water is shown in the Sodium and Potassium in Water movie eChapter 14.14). Write and balance the equation for this reaction. Is this an oxidation-reduction reaction If so, identify the oxidizing and reducing agents. 

Reactions in which there is a change in the charges of some or all of the reactants are called oxidation-reduction (redox) reactions. Because there are changes in charge, equations can be considered with the inclusion of electrons showing the movement of electrons from one participant in the reaction to another. The reaction of metallic copper and sulfur is an example of an oxidation-reduction reaction. 

Every chemical reaction has a driving force—a reason why it proceeds as it does. We can say that the reason why oxidation-reduction reactions proceed is because one atom is giving up electrons and another is accepting them. We can also make the statement a bit more forcefully by saying that an element is grabbing electrons from another. There is some terminology, discussed below, that is based on these ideas. Consider this equation... 

Two general styles are used when writing oxidation-reduction reactions. The first is to include all species that are in the reaction—that is to say that there is nothing left out, even if it is a spectator. In this style, acids and bases are written into the equation. The second style leaves out spectators. Because the anion in acids and the cation in bases are often spectators (ions common with one or more of the compounds in the reaction), the... 

Half-reactions can be added to produce a net reaction, which is the oxidation-reduction reaction. However, this summation cannot be performed unless the electron numbers are the same on both sides of the reaction by agreement among chemists, electrons are not written into summation reactions. The way in which adjustments are made is to preserve the ratio of coefficients in the individual balanced half-reaction by multiplying all of the participants in an equation by the same number. The goal is to have the same number of electrons on opposite sides of the half-reactions. The electrons will then algebraically cancel when the half-reactions are added. Since the summation equation should not have coefficients divisible by a common factor, it is customary to choose numbers that will yield the least number of electrons for cancellation. 

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