Direct Measurements of the Reaction NH2 + H2 → NH3 + H at Temperatures from 1360 to 2130 K
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G. Friedrichs
The reaction NH2 + H2 → NH3 + H (11) was investigated behind shock waves in the temperature range from 1360 to 2130 K. Time histories of NH2 were measured by frequency modulation (FM) spectroscopy. The rate constant was determined to be k11 = 4.5 · 1013 · exp[-61 kJ mol-1/RT] cm3 mol-1 s-1 (Δlog k11 = ±0.15, ΔEa = ±9 kJ/mol).
According to recent literature values the reverse reaction NH3 + H → NH2 + H2 (-11) can be described by k-11 = 1.5 · 107 · T2.0 · exp(-47 kJ mol-1/RT) cm3 mol-1 s-1 for the temperature range of 400 to 2500 K. On the basis of k-11 and by using the enthalpy of formation of ΔfHo298 Κ(NH2) = 190 kJ/mol, which was determined in a previous study [1], via detailed balance the following expression for the forward reaction (11) was obtained for a temperature range of 400 to 2200 K: k11 = 1.5 · 104 · T2.6 · exp(-25 kJ mol-1/RT) cm3 mol-1 s-1. This expression is in very good agreement with the reported experimental values for k11.
Die Reaktion NH2 + H2 → NH3 + H (11) wurde bei Temperaturen von 1360 bis 2130 K hinter Stoßwellen untersucht. NH2-Konzentration-Zeit-Profile wurden mittels frequenzmodulierter (FM) Spektroskopie aufgenommen. Die Geschwindigkeitskonstante wurde zu k11 = 4.5 · 1013 · exp[-61 kJ mol-1/RT] cm3 mol-1 s-1 (Δ log k11 = ±0.15, Δ Ea = ±9 kJ/mol) bestimmt.
Auf Grundlage neuerer Literaturwerte kann die Geschwindigkeitskonstante der Rückreaktion, NH3 + H → NH2 + H2 (-11), im Temperaturbereich von 400 bis 2500 K durch k-11 = 1.5 ·107· T2.0 · exp(-47 kJ mol-1/RT) cm3 mol-1 s-1 beschrieben werden. Ausgehend von k-11 und von einer Bildungsenthalpie des NH2-Radikals von ΔfHo298 Κ(NH2) = 190 kJ/mol, die in einer vorhergehenden Arbeit [1] ermittelt wurde, kann über die Gleichgewichtskonstante der folgende Ausdruck für die Geschwindigkeitskonstante der Hinreaktion (11) angegeben werden (400-2200 K): k11 = 1.5 · 104 · T2.6 · exp(-25 kJ mol-1/RT) cm3 mol-1 s-1. Dieser Ausdruck gibt die experimentell ermittelten k11-Werte sehr gut wieder.
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- Correlation of Adiabatic States between Perturbed Rotor and Renner-Teller Limits for a Closed-Shell Ion + Open Shell Diatom System
- Testing Intermolecular Potentials with Scattering Experiments: He-CO Rotationally Inelastic Collisions
- Collision-Induced Dissociation Dynamics of the [OCS · C2H2]+ Complex. A Combined Experimental and Theoretical Study
- Temperature Dependence of Collisional Energy Transfer in Highly Excited Aromatics Studied by Classical Trajectory Calculations
- Coupling Across Bonds: Ab Initio Calculations for the Anharmonic Vibrational Resonance Dynamics of the Coupled OH and CH Chromophores in Trans Formic Acid HCOOH
- A Saturated LIF Study on the High Pressure Limiting Rate Constant of the Reaction CN + NO + M → NCNO + M between 200 and 600 K
- High Resolution Electron Ionization of N2O Clusters: Appearance Energies
- Direct Measurements of the Reaction NH2 + H2 → NH3 + H at Temperatures from 1360 to 2130 K
Artikel in diesem Heft
- Correlation of Adiabatic States between Perturbed Rotor and Renner-Teller Limits for a Closed-Shell Ion + Open Shell Diatom System
- Testing Intermolecular Potentials with Scattering Experiments: He-CO Rotationally Inelastic Collisions
- Collision-Induced Dissociation Dynamics of the [OCS · C2H2]+ Complex. A Combined Experimental and Theoretical Study
- Temperature Dependence of Collisional Energy Transfer in Highly Excited Aromatics Studied by Classical Trajectory Calculations
- Coupling Across Bonds: Ab Initio Calculations for the Anharmonic Vibrational Resonance Dynamics of the Coupled OH and CH Chromophores in Trans Formic Acid HCOOH
- A Saturated LIF Study on the High Pressure Limiting Rate Constant of the Reaction CN + NO + M → NCNO + M between 200 and 600 K
- High Resolution Electron Ionization of N2O Clusters: Appearance Energies
- Direct Measurements of the Reaction NH2 + H2 → NH3 + H at Temperatures from 1360 to 2130 K
