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Kinetics of iodination of hydrogen sulfide by iodine and the heat of formation of the SH radical
Author(s) -
Hwang R. J.,
Benson S. W.
Publication year - 1979
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550110604
Subject(s) - chemistry , bond dissociation energy , halogenation , standard enthalpy of formation , kinetics , iodine , hydrogen sulfide , activation energy , dissociation (chemistry) , kinetic energy , yield (engineering) , hydrogen atom , atmospheric temperature range , sulfide , medicinal chemistry , hydrogen , gas phase , sulfur , organic chemistry , thermodynamics , alkyl , physics , quantum mechanics
The kinetics of the gas‐phase thermal iodination of hydrogen sulfide by I 2 to yield HSI and HI has been investigated in the temperature range 555–595 K. The reaction was found to proceed through an I atom and radical chain mechanism. Analysis of the kinetic data yields log k (l/mol·sec) = (11.1 ± 0.18) – (20.5 ± 0.44)/θ, where θ = 2.303 RT , in kcal/mol. Combining this result with the assumption E −1 = 1 ± 1 kcal/mol and known values for the heat of formation of H 2 S, I 2 , and HI, Δ H f,298 0 (SH) = 33.6 ± 1.1 kcal/mol is obtained. Then one can calculate the dissociation energy of the HSH bond as 90.5 ± 1.1 kcal/mol with the well‐known values for Δ H f,298 0 of H and H 2 S.