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Autoxidation kinetics of aqueous nitric oxide
P C Ford1, D A Wink, D M Stanbury
1Department of Chemistry, University of California, Santa Barbara 97106.
FEBS Letters
|July 12, 1993
Summary
The autoxidation of nitric oxide (NO) in water follows a specific rate law, -d[NO]/dt = 4kaq[NO]2[O2]. This study corrects previous findings, establishing the accurate kinetics for this important chemical reaction.
Area of Science:
- Environmental Chemistry
- Chemical Kinetics
- Atmospheric Chemistry
Background:
- Nitric oxide (NO) readily autoxidizes in aqueous solutions.
- Understanding the kinetics of NO autoxidation is crucial for environmental and atmospheric chemistry.
- Previous studies have proposed differing rate laws for this reaction.
Purpose of the Study:
- To critically evaluate and determine the correct rate law for the autoxidation of aqueous nitric oxide.
- To resolve discrepancies in previously reported kinetic data.
- To provide accurate kinetic parameters for NO autoxidation.
Main Methods:
- Review and analysis of existing reports on nitric oxide autoxidation kinetics.
- Thermodynamic and kinetic modeling of aqueous NO reactions.
- Comparison of predicted reaction rates with experimental data.
Main Results:
- The correct rate law for aqueous nitric oxide autoxidation is identified as -d[NO]/dt = 4kaq[NO]2[O2].
- The rate constant (kaq) was determined to be 2 x 10^6 M^-2.s^-1 at 25°C.
- A previously reported rate law, which was zero order in NO, was found to be incorrect.
Conclusions:
- The established rate law provides a precise description of NO autoxidation in aqueous environments.
- Accurate kinetic data are essential for modeling atmospheric processes involving nitrogen oxides.
- This study refines the understanding of NO's environmental fate and reactivity.