title: Kinetics of the iodate reduction by hydrogen peroxide and relation with the Briggs-Rauscher and Bray-Liebhafsky oscillating reactions.
abstract: The iodate reduction by hydrogen peroxide in acidic solutions is part of the Bray-Liebhafsky and Briggs-Rauscher oscillating reactions. At low hydrogen peroxide concentrations, typical of the Bray-Liebhafsky reaction, its rate law is -d[IO(-)(3)]/dt = (k'(R) + k"(R)[H(+)])[IO(-)(3)][H(2)O(2)] with k'(R) = 1.3 × 10(-7)(20°), 7.8 × 10(-7) (39°), 1.4 × 10(-5) M(-1) s(-1) (60°) and k"(R) = 1.5 × 10(-5) (25°), 6.2 × 10(-5) (39°), 6.3 × 10(-4) M(-2) s(-1) (60°). It is explained by a non-radical mechanism. At high hydrogen peroxide concentrations, typical of the Briggs-Rauscher reaction, a new reaction pathway appears with a rate more than proportional to [H(2)O(2)](2) and nearly independent of [IO(3)(-)] > 0.01 M. This pathway is inhibited by scavengers of free radicals. We suggest that it has a radical mechanism starting with IOH + H(2)O(2)⇌ IOOH + H(2)O and IOOH+H(2)O(2)→ IO˙ + H(2)O+HOO˙.
authors.affiliation: Faculty of Applied Sciences, Université Libre de Bruxelles, CP165/63, Av. F. Roosevelt 50, 1050 Brussels, Belgium. gschmitz@ulb.ac.be
authors.forename: Guy
authors.initials: G
authors.lastname: Schmitz
authors.forename: Stanley
authors.initials: S
authors.lastname: Furrow
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry*; D007452:Iodates / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D013816:Thermodynamics
chemical_list: D007452:Iodates; D006861:Hydrogen Peroxide