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The Kinetics of the thermal oxidation of NO in solid oxygen between 13 and 29 K; direct observation of the reaction of (NO) 2 and oxygen
Author(s) -
Smith George R.,
Guillory William A.
Publication year - 1977
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550090610
Subject(s) - chemistry , kinetics , oxygen , reaction rate constant , quantum tunnelling , phase (matter) , oxygen atom , thermocouple , chemical kinetics , thermal , analytical chemistry (journal) , kinetic isotope effect , order of reaction , thermodynamics , atomic physics , organic chemistry , deuterium , molecule , condensed matter physics , engineering , electrical engineering , physics , quantum mechanics
The kinetics of the reaction of cis ‐(NO) 2 with solid oxygen to form iso ‐N 2 O 4 have been studied between 13 and 29 K. The overall reaction is pseudo first order in cis ‐(NO) 2 , and solid oxygen serves both as a reactant and the matrix. The pseudo‐first‐order rate constants are calculated to be k ( 14 N) = 4.25 × 10 −2 exp(‐103/ RT ), and k ( 15 N) = 3.00 × 10 −2 exp(‐105/ RT ) sec −1 , based on temperature measurements from a thermocouple junction which may be at most three degrees lower than the actual reacting film. Most significantly, however, 14 k / 15 k = 1.55 at∼13 K. The condensed phase reaction has been compared to that observed in the gas phase, and the extremely small pre‐exponential factors and large isotope effects have been discussed in terms of tunneling corrections and orientational constraints. It is suggested that the form of the crystal plays an integral role in the observed process.