Oxidizing agent relative strengths

Use standard potentials (Table 18.1) torn compare the relative strengths of ditferent oxidizing agents different reducing agents. (Example 18.2 Problems 9-18) 9,10,16,18... 

Lacking a table of standard electrode potentials, or one that is adequate, what guidelines can be used to identify oxidizing and reducing agents, and to estimate their relative strengths Here are a few. 

A procedure for the direct determination of the sulfate, sulfide, pyritic, and organic sulfur in a single sample of coal has been reported by McGowan and Markuszewski (17). The method uses various strengths of perchloric acid as the selective oxidizing agent. The results obtained for the analysis of three coals were comparable to ASTM results and the relative standard deviations for nine sulfate, four pyritic, six organic, and four total recovered sulfur determinations were 2.7, 3.4, 2.4, and 2.4%, respectively. 

Table of relative strengths of oxidizing and reducing agents (see table on the following page)... 

The magnitudes of these electrode potentials indicate the relative strength of the four ionic species as electron acceptors (oxidizing agents) that is, in decreasing strength, Ag > H+ > Cd > Zn +. 

FIGURE 4.4 Relative strength of oxidant (oxidizing agent or electron acceptor) and reductant (reducing agent or electron donor). 

The electron transfer producing free radicals as shown above is preceded by the formation of unstable coordination complexes of the metal ions with alkyl hydroperoxides. The relative importance of Reaction 1.76 and Reaction 1.77 depends upon the relative strength of the metal ion as an oxidizing or reducing agent. When the metal ion has two valence states of comparable stability, both Reaction 1.76 and Reaction 1.77 will occur, and a trace amount of the metal can convert a large amount of peroxide to free radicals according to the sum of the two reactions (Reaction 1.78). This is true of compounds of metals such as Fe, Co, Mn, Cu, Ce, and V, commonly called transition metals. 

Because they contain only C — C and C—H bonds, most alkanes are relatively unreac-tive. At room temperature, for example, they do not react with acids, bases, or strong oxidizing agents. Their low chemical reactivity, as noted in Section 24.1, is due primarily to the strength and lack of polarity of C—C and C—H bonds. 

Figure 20.11 Relative strengths of oxidizing and reducing agents. 

EXERCISE 20.8 Determining Relative Strengths of Oxidizing Agents... 

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