Sulfur oxidation numbers

The compound S02NH3 could be (LX) or a thionyl ammonium sulfite (65), but it may also be considered as a simple adduet of NH3 and S02 (LXII). It shows a strong tendency to disproportionation to compounds with a sulfur oxidation number of +6 and others with sulfur in a lower oxidation state (47). 

In the Maumee Chemical [60] plan for saccharin, there is a curiosity with respect to the oxidation number of the sulfur atom in the source material as shown in step 1 of the following scheme. It conld be either sodium sulfide (oxidation number = -2) or elemental sulfur (oxidation number = 0). In this case, the arithmetic mean of these valnes was nsed as the oxidation number of the sulfur atom in the starting material (oxidation number = -1) which, by the way, corresponds to the oxidation number of sulfur in disodium disulfide that is generated in situ from sodium sulfide and elemental sulfur. 

But in the covalent compound SCI2, you have seen that the sulfur oxidation number of +2 was obtained by an imaginary distortion of the distribution of electrons, so that the shared electron pairs in the covalent bonds are transferred completely to the more electronegative chlorine. The charge carried by sulfur in the real SCI2 molecule must therefore be less than the oxidation number of +2. To emphasize this, oxidation numbers are often written as Roman numerals in parentheses after the element. Thus, SCI2 is written as sulfur(II) chloride, and SO2 as sulfur(IV) oxide. Oxidation numbers can be used to balance redox equations, which we consider next. 

The ten substances listed below contain sulfur. Work out the oxidation number of sulfur in each one. Then present your results in the form of a table, showing the substances in order of increasing sulfur oxidation number. 

Olefin synthesis starts usually from carbonyl compounds and carbanions with relatively electropositive, redox-active substituents mostly containing phosphorus, sulfur, or silicon. The carbanions add to the carbonyl group and the oxy anion attacks the oxidizable atom Y in-tramolecularly. The oxide Y—O" is then eliminated and a new C—C bond is formed. Such reactions take place because the formation of a Y—0 bond is thermodynamically favored and because Y is able to expand its coordination sphere and to raise its oxidation number. 

Raw material input to petroleum refineries is primarily crude oil however, petroleum refineries use and generate an enormous number of chemicals, many of which leave the facilities as discharges of air emissions, wastewater, or solid waste. Pollutants generated typically include VOCs, carbon monoxide (CO), sulfur oxides (SOJ, nitrogen oxides (NOJ, particulates, ammonia (NH3), hydrogen sulfide (HjS) metals, spent acids, and numerous toxic organic compounds. 

Gmelin Handbook of Inorganic Chemistry, 8 ed., Sulfur-Nitrogen Compounds, Part 2 Compounds with Sulfur of Oxidation Number IV, Springer-Verlag, Berlin (1985). 

This fictitious charge is called the oxidation number of sulfur ... 

According to the oxidation number bookkeeping, the two electrons released in the HS03 -HSO - half-reaction (75) are associated with the change in oxidation number of sulfur from +4 to +6. 

In reaction (76) the oxidation number of sulfur changes from +4 to 4-6. According to this, two electrons are released by each sulfur atom oxidized. Show that these electrons are gained by oxygen if we assume oxygen has oxidation number equal to zero in O2. 

If the gain in oxidation number by sulfur is to equal the loss by manganese, then five atoms of sulfur must react with two atoms of manganese ... 

Verify that reaction (23) is an oxidation-reduction reaction and that the oxidation number change of carbon is balanced by the oxidation number change of the sulfur. 

Sulfur reacts with molecular oxygen to form compounds in which sulfur is assigned positive oxidation numbers, +4 and +6. The reactions are those used in the manufacture of sulfuric acid (see Chapter 13) ... 

Cupric sulfide, copper(II) sulfide, reacts with hot nitric acid to produce nitric oxide gas, NO, and elemental sulfur. Only the oxidation numbers of S and N change. Write the balanced equation for the reaction. 

SOLUTION The process is oxidation if the oxidation number of sulfur increases, reduction if it decreases. We need to assign the oxidation numbers of sulfur in S02 and S042, then compare them. To assign an oxidation number to sulfur we represent that number by x and solve for x, by using the rules in Toolbox K.l. The oxidation number of oxygen is —2 in both compounds. 

Therefore, the oxidation number of sulfur in S042 is x = +6. We can conclude that sulfur is more highly oxidized in the sulfate ion than in sulfur dioxide. Therefore, the conversion of S02 to S042- is an oxidation. 

Self-Test K.2A Find the oxidation numbers of sulfur, phosphorus, and chlorine in (a) H2S (b) P406 (c) CIO". 

Sulfur can exist in both positive and negative oxidation states. What is the maximum (a) positive and (b) negative oxidation number that sulfur can have (c) Write the electron configuration for each of these states, (d) Explain how you arrived at these values. 

Precipitation over North America gradually becomes more acidic from west to east, especially in industrialized areas of the Northeast. This acid rain may be a result of the release of nitrogen and sulfur oxides into the atmosphere. The colors and numbers (see key) indicate pH measured at field laboratories in 2004. Data from National Atmospheric Deposition Program/National Trends Network http //nadp.sws.uiuc.edu. 

The oxidation number of sulfur in sulfur dioxide and the sulfites is +4, an intermediate value in sulfur s range from —2 to +6. Hence, these compounds can act as either oxidizing agents or reducing agents. By far the most important reaction of sulfur dioxide is its slow oxidation to sulfur trioxide, S03 (13), in which sulfur has the oxidation number +6 ... 

Sflf-Test 1S.4A What is the oxidation number of sulfur in (a) the dithionate ion, S2062 (b) the thiosulfate ion, S2032- ... 

The principal use of sodium chlorate is as a source of chlorine dioxide, C102. The chlorine in C102 has oxidation number +4, and so the chlorate must be reduced to form it. Sulfur dioxide is a convenient reducing agent for this reaction ... 

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