Transitions in Order and Molecularity with Temperature in Gaseous Metal Oxidation Reactions. The Sb-O2 System
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B. Cosic
Examples of reactions which are termolecular near room temperature and gradually switch over to complex-forming bimolecular reactions with increasing temperature are discussed. The Sb/O2 system, which is known from D. Husain´s work to be termolecular at 300 K, has been studied here from 1165-1495 K at 12 to 52 mbar in a high-temperature fast-flow reactor (HTFFR). Sb was vaporized from a crucible and atomic resonance absorption spectrometry was used to measure the rates of Sb consumption. Under these conditions the reaction, identified as Sb + O2 → SbO + O, is pressure-independent with k(T) = 6.3×10-11 exp (-9107 K/T) cm3 molecule-1 s-1. The 2σ precision limits are ±8% and the corresponding estimated accuracy limits are ±24%. The results suggest that D0(Sb-O) = 444±28 kJ mol-1. The results are compared to those of other endothermic metal-atom O2 abstraction reactions, all of which have pre-exponentials on the order of 10-10 cm3 molecule-1 s-1 and activation energies for abstraction close to the endothermicity. This allows assessments of the relative importance of bi-, and ter- molecular kinetics, as illustrated for As + O2.
Articles in the same Issue
- Approximate Factorization of Molecular Potential Surfaces II. Internal Rotors
- A Thermodynamic Method of Estimating Anharmonic Molecular Densities of States
- The Heterogeneous Kinetics of the Reactions ClONO2 + HX/ice (X = Br, I), BrONO2 + HI/ice and the Reactivity of the Interhalogens BrCl, ICl and IBr with HX/ice (X = Cl, Br, I) in the Temperature Range 180 to 205 K
- Collisional Deactivation of Highly Vibrationally Excited SO2: A Time-Resolved FTIR Emission Spectroscopy Study
- Transitions in Order and Molecularity with Temperature in Gaseous Metal Oxidation Reactions. The Sb-O2 System
- Kinetic Analysis of Complex Chemical Activation and Unimolecular Dissociation Reactions using QRRK Theory and the Modified Strong Collision Approximation
- Chemical Reactions in Ionic Molecular Aggregates. An ab initio and R2PI-Study of the Halogenbenzene/Ammonia System
- Internal Conversion with 3,5-Dimethyl-4-(methylamino)benzonitrile in Alkane Solvents
Articles in the same Issue
- Approximate Factorization of Molecular Potential Surfaces II. Internal Rotors
- A Thermodynamic Method of Estimating Anharmonic Molecular Densities of States
- The Heterogeneous Kinetics of the Reactions ClONO2 + HX/ice (X = Br, I), BrONO2 + HI/ice and the Reactivity of the Interhalogens BrCl, ICl and IBr with HX/ice (X = Cl, Br, I) in the Temperature Range 180 to 205 K
- Collisional Deactivation of Highly Vibrationally Excited SO2: A Time-Resolved FTIR Emission Spectroscopy Study
- Transitions in Order and Molecularity with Temperature in Gaseous Metal Oxidation Reactions. The Sb-O2 System
- Kinetic Analysis of Complex Chemical Activation and Unimolecular Dissociation Reactions using QRRK Theory and the Modified Strong Collision Approximation
- Chemical Reactions in Ionic Molecular Aggregates. An ab initio and R2PI-Study of the Halogenbenzene/Ammonia System
- Internal Conversion with 3,5-Dimethyl-4-(methylamino)benzonitrile in Alkane Solvents
