Kinetics and mechanism of the reaction between chlorine(III) and molecular bromine

Journal Article · Thu Dec 04 04:00:00 EST 1986 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100283a022· OSTI ID:6953201

Valdes-Aguilera, O; Boyd, D W; Epstein, I R; Kustin, K

Reaction between chlorine(III) and bromine results in the oxidation of chlorine(III) to chlorine dioxide according to 2ClO/sub 2//sup -/ (or 2HClO/sub 2/) + Br/sub 2/ ..-->.. 2ClO/sub 2/ + 2Br/sup -/ (+ 2H/sup +/) (reaction A). The kinetics of reaction A were studied by stopped-flow spectrophotometry in the pH range 0.58-4.23, leading to a proposed mechanism in which the rate-determining step is BrClO/sub 2/ + ClO/sub 2//sup -/ (or HClO/sub 2/) ..-->.. 2ClO/sub 2/ + Br/sup 2/ (+ H/sup +/) (reaction B). The rate data obtained at 25 /sup 0/C and ionic strength 0.66 M yield the rate constant of reaction B, k/sub B/ = (2.94 +/- 0.25) x 10/sup 3/ M/sup -1/ s/sup -1/, and the acidity constant of the intermediate BrClO/sub 2/H..mu.., K/sub a/ = (1.23 +/- 0.02) x 10/sup -2/ M. At pH 7.41 bromine is present as BrOH and Cl(III) as ClO/sub 2//sup -/. Consequently the rate constant for the reaction between BrOH and ClO/sub 2//sup -/, 20.6 M/sup -1/s/sup -1/, indicates that BrOH is less reactive than Br/sub 2/ toward Cl(III). Formation of the intermediate is a complex process involving attack by chlorine(III) on molecular bromine followed by electron transfer and leaving of bromide ion.

• Research Organization: Brandeis Univ., Waltham, MA
• OSTI ID: 6953201
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:25; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
BROMINE
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHLORINE
DATA
ELECTRON TRANSFER
ELEMENTS
EXPERIMENTAL DATA
HALOGENS
INFORMATION
KINETICS
MEDIUM TEMPERATURE
NONMETALS
NUMERICAL DATA
PH VALUE
REACTION INTERMEDIATES
REACTION KINETICS
SPECTROPHOTOMETRY