Concepts from Chemical Reaction Kinetics - Elements of Environmental Engineering: Thermodynamics and Kinetics - page 257

The following two reactions are of importance in both atmospheric
moisture and seawater:
(a) oxidation of H 2 S by peroxymonosulfate (an important oxi-
dant in clouds), HSO 5 + SO 2 −

5

→ 2SO 2 −
4

+ O 2 + H + , with k =

0.1 L/mol/s at 298 K in distilled water and
(b) oxidation of nitrite by ozone to form nitrate, NO 2

+ O 3 → NO 3 +

O 2 , with k = 1.5 × 10 − 5 L/mol/s at 298 K in distilled water.
Estimate the rate constants of the above reactions in the natural waters
given above.
5.16 2 The following rate data were reported by Sung and Morgan (1980) for the
homogeneous oxidation of Fe(II) to Fe(III) in aqueous solution:

k (L 2 /mol 2 /atm/min) I (M)

4.0 × 10 13

0.009

3.1 × 10 13 0.012

2.9 × 10 13 0.020

2.2 × 10 13 0.040

1.8 × 10 13

0.060

1.2 × 10 13

0.110

Obtain the product of the charges of the species involved in the reaction.
Tamura et al. (1976) proposed the following rate-limiting step for the reac-
tion: FeOH + + O 2 OH − → Fe ( OH ) 2 + O 2 . Does your result support

this contention?
5.17 3 Corrosioninwastewatercollectionsystemsbysulfuricacidgeneratedfrom
H 2 S is a nuisance. Oxidation of H 2 SbyO 2 is therefore an important issue.
The rate of this reaction is accelerated by catalysts. Kotranarou and Hoff-
mann (1991) discussed the use of Co II TSP (a tetrasulfophthalocyanine)
as a possible catalyst for auto-oxidation of H 2 S in wastewater. The rate
constant for the reaction was of the form k = k [ O 2 ] /(K +[ O 2 ] ) . The
following reaction scheme was suggested:
Co II (TSP) 4 −
2

2Co II (TSP) 2 − ,

Co II (TSP) 2 − + HS − HSCo II (TSP) 3 − ,

HSCo II (TSP) 3 − + O 2 HSCo II (TSP)(O −• ) 3 − ,

2

HSCo II (TSP)(O −•
2

) 3 − + HS − HSCo II (TSP)(O −•
2

)( HS ) 4 − ,

slow

HSCo II (TSP)(O −•
2

)( HS ) 4 − −−−→ HSCo II (TSP)(O 2 −

2

) 5 − S 0

+ H,

fast

−−→ HSCo II (TSP) 3 − + H 2 O 2 .
Obtain the rate expression for − d [ S ( − II ) ] / d t , where S ( − II ) is the reduced
form of sulfur in the above reaction scheme. Simplify the expression for
thepseudo-first-orderkineticstoshowthattherateconstanthasthegeneral
form given above.
5.18 3 Different isomers of HCH are abundant pesticides in the world's oceans
and lakes. They are also known to be present in atmospheric particles and

HSCo II (TSP)(O 2 −
2

) 5 − + 2H +