The UNT College of Arts and Sciences educates students in traditional liberal arts, performing arts, sciences, professional, and technical academic programs. In addition to its departments, the college includes academic centers, institutes, programs, and offices providing diverse courses of study.
Article on a computational study of the thermochemistry of N₂O₅ and the Kinetics of the Reaction N₂O₅ + H₂O → 2 HNO₃.
Physical Description
12 p.
Notes
Abstract: The multistructural method for torsional anharmonicity (MS-T) is employed to compute anharmonic conformationally averaged partition functions which then serve as the basis for the calculation of thermochemical parameters for N2O5 over the temperature range 0–3000 K, and thermal rate constants for the hydrolysis reaction N2O5 + H2O → 2 HNO3 over the temperature range 180–1800 K. The M06-2X hybrid meta-GGA density functional paired with the MG3S basis set is used to compute the properties of all stationary points and the energies, gradients, and Hessians of nonstationary points along the reaction path, with further energy refinement at stationary points obtained via single-point CCSD(T)-F12a/cc-pVTZ-F12 calculations including corrections for core–valence and scalar relativistic effects. The internal rotations in dinitrogen pentoxide are found to generate three structures (conformations) whose contributions are included in the partition function via the MS-T formalism, leading to a computed value for S°298.15(N2O5) of 353.45 J mol–1 K–1. This new estimate for S°298.15(N2O5) is used to reanalyze the equilibrium constants for the reaction NO3 + NO2 = N2O5 measured by Osthoff et al. [ Phys. Chem. Chem. Phys. 2007, 9, 5785−5793] to arrive at ΔfH298.15°(N2O5) = 14.31 ± 0.53 kJ mol–1 via the third law method, which compares well with our computed ab initio value of 13.53 ± 0.56 kJ mol–1. Finally, multistructural canonical variational-transition-state theory with multidimensional tunneling (MS-CVT/MT) is used to study the kinetics for hydrolysis of N2O5 by a single water molecule, whose rate constant can be summarized by the Arrhenius expression 9.51 × 10–17 (T/298 K)3.354 e(−7900K/T) cm3 molecule–1 s–1 over the temperature range 180–1800 K.
Reprinted with permission from the Journal of Physical Chemistry A. Copyright 2014 American Chemical Society.
Publication Title:
Journal of Physical Chemistry A
Volume:
118
Issue:
48
Page Start:
11405
Page End:
11416
Peer Reviewed:
Yes
Collections
This article is part of the following collection of related materials.
UNT Scholarly Works
Materials from the UNT community's research, creative, and scholarly activities and UNT's Open Access Repository. Access to some items in this collection may be restricted.
Alecu, I. M. & Marshall, Paul.Computational Study of the Thermochemistry of N₂O₅ and the Kinetics of the Reaction N₂O₅ + H₂O → 2 HNO₃,
article,
November 7, 2014;
[Washington, D.C.].
(https://digital.library.unt.edu/ark:/67531/metadc488165/:
accessed April 18, 2024),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT College of Arts and Sciences.