Oxidation-reduction equations alternative method

In this problem, we describe an alternative method for balancing equations for oxidation-reduction reactions. The method is similar to the method given previously in Tables 5.5 and 5.6, but it places more emphasis on the assignment of oxidation states. (The method summarized in Tables 5.5 and 5.6 does not require you to assign oxidation states.) An emphasis on oxidation states is warranted because oxidation states are useful not only for keeping track of electrons but also for predicting chemical properties. The method is summarized in the table above. 

Use the alternative method described above to balance the following oxidation-reduction equations. 

The reduction of nitro compounds should initially produce nitroso compounds. This area has not been systematically explored because the nitroso group can be more easily introduced by alternative methods such as direct nitrosation, condensation and oxidative procedures. - In fact, there have been few instances in which nitroso compounds have been isolated as intermediates in reductions of nitro compounds. For example, it was initially believed that w-trifluoromethylnitrobenzene produced the corresponding nitroso compound upon reduction, but subsequently the product was shown to be w-trifluoromethylazox-ybenzene. - Low yields of an intramolecular dimeric, nitroso compound, benzo[c]cinnoline dioxide (1), can be obtained by reducing 2,2 -dinitrobiphenyl with zinc or sodium sulfide (equation I). - ... 

An alternative to the oxidation-number method for balancing redox reactions is the half-reaction method. The key to this method is to realize that the overall reaction can be broken into two parts, or half-reactions. One half-reaction describes the oxidation part of the process, and the other half-reaction describes the reduction part. Each half is balanced separately, and the two halves are then added to obtain the final equation. Let s look at the reaction of aqueous potassium dichromate (K2Cr2C>7) with aqueous NaCl to see how the method works. The reaction occurs in acidic solution according to the unbalanced net ionic equation... 

In the future, it seems likely that most processes that currently entail the discharge of SO2 will have to be adapted with the introduction of scrubbers . Two main methods can be employed for this either the reduction of SO2 to snllur using the Claus process or, alternatively, neutralization nsing milk of lime (equation 18) to give either calcium sulfite or, with complete oxidation, calcium sulfate (gypsum). 

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