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Kinetic study of the reactions Br + IBr→I + Br 2 and I + Br 2 →Br + IBr
Author(s) -
Bedjanian Y.,
le Bras G.,
Poulet G.
Publication year - 1998
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/(sici)1097-4601(1998)30:12<933::aid-kin8>3.0.co;2-y
Subject(s) - chemistry , reaction rate constant , enthalpy , kinetics , equilibrium constant , kinetic energy , torr , chemical kinetics , analytical chemistry (journal) , reaction rate , standard enthalpy of formation , molecule , thermodynamics , organic chemistry , catalysis , physics , quantum mechanics
The kinetics of the title reactions have been studied using the discharge‐flow mass spectrometic method at 296 K and 1 torr of helium. The rate constant obtained for the forward reaction Br+IBr→I+Br 2 (1), using three different experimental approaches (kinetics of Br consumption in excess of IBr, IBr consumption in excess of Br, and I formation), is: k 1 =(2.7±0.4)×10 −11 cm 3 molecule −1 s −1 . The rate constant of the reverse reaction: I+Br 2 →Br+IBr (−1) has been obtained from the Br 2 consumption rate (with an excess of I atoms) and the IBr formation rate: k −1 =(1.65±0.2)×10 −13 cm 3 molecule −1 s −1 . The equilibrium constant for the reactions (1,−1), resulting from these direct determinations of k 1 and k −1 and, also, from the measurements of the equilibrium concentrations of Br, IBr, I, and Br 2 , is: K 1 = k 1 / k −1 =161.2±19.7. These data have been used to determine the enthalpy of reaction (1), Δ H 298 °=−(3.6±0.1) kcal mol −1 and the heat of formation of the IBr molecule, Δ H f ,298 °(IBr)=(9.8±0.1) kcal mol −1 . © 1998 John Wiley & sons, Inc. Int J Chem Kinet 30: 933–940, 1998