Rate of exchange of hydrogen and deuterium behind reflected shock waves. Dynamic analysis by time-of-flight mass spectrometry

Kern, R. D.; Nika, G. G.

doi:10.1021/j100680a036

Cited by 20 publications

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“…This is not supported by the experimental results. 4 This investigation of the self-exchange supports the nonlinear time dependence of product formation re-ported previously for isotopic exchange reactions.8 '4 It further permits an appraisal of the equilibrium constant in good agreement with the calculated value,…”

Section: Discussionsupporting

confidence: 84%

“…The investigation of the HD self-exchange provides two opportunities to check the consistency of the experimental results reported for the forward reaction. 4 First, the magnitude of the activation energy should be the same since the overall reaction is thermoneutral. Second, a nonlinear time dependence for the growth of products H2 and D2 should be observed.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic sampling of the deuterium hydride self-exchange behind reflected shock waves

Kern¹,

Nika²

1971

J. Phys. Chem.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Dynamic sampling of the deuterium hydride self-exchange behind reflected shock waves

Kern¹,

Nika²

1971

J. Phys. Chem.

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“…Hexagonal H 6 has been identified by numerous theoretical investigations as the transition state for the degenerate exchange of three H 2 molecules. − The experimental investigations, although extensive, are inconclusive. − The energy of H 6 ( D 6 h ) is ca. 30 kcal/mol lower than 2H 2 + 2H (i.e., a process involving dissociation of a hydrogen molecule).…”

Section: Introductionmentioning

confidence: 99%

Are theD_m_hSymmetric H_x^qRings with 4n+ 2 σ-Electrons and Hydrogen Clusters Aromatic?

Jiao¹,

Schleyer²,

Glukhovtsev³

1996

J. Phys. Chem.

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The D mh symmetric H x q rings, H 5 -(D 5h , D 4h ), H 5 + (C 2V ), H 6 (D 6h , D 5h ), H 7 + (D 7h , D 6h ), H 8 2+/2-(D 8h ), H 9 + (D 3h ), H 9 -(D 9h , D 8h ), and H 10 (D 10h , D 9h ) are considered as possible analogs of the Hu ¨ckel 4n + 2 electron aromatic annulene systems. While aromatic character (due to ring current effects) is indicated by the magnetic susceptibility exaltations (Λ) and large magnetic susceptibility anisotropies, χ anis (derived from IGLO computations of the magnetic properties), most of these hydrogen ring systems are higher order saddle points. The exceptions are transition structures: H 6 (D 6h ), which can be compared with benzene, and H 10 (D 10h ) which is even less favorable energetically. On the basis of energetic, structural, and magnetic criteria, aromaticity can result from cyclic delocalization of σas well as π-electrons. On the basis of the diamagnetic exaltations, "spherical aromaticity" is illustrated by H 6 2and H 8 , both with O h symmetry and eight σ-electrons as well as H 4 2+ with T d symmetry and only two σ-electrons, even though these species are artificial, higher order saddle points. The Hu ¨ckel 4n electron antiaromatic H 3 -(D 3h ), H 4 (D 4h ), H 5 + (D 5h , D 4h ), and H 8 (D 8h ) triplet states have been computed. Both H 4 (D 4h ) and H 8 (D 8h ) have negative (unfavorable) energies of concert relative to two H atoms and the appropriate number of H 2 molecules.

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“…Most of the shock tube work during the past 12 years concerned with exchange systems has dealt with D2 reacting with a variety of relatively simple molecules: NH3,2 C2H2,3 CH4,4 H2S,5 HC1,6 HCN,7 HBr,8 and H2.9, 10 The single-pulse shock tube technique has established the order for the reactants and inert gas and the activation energy for many of these reactions.2'43,5,9 Dynamic sampling of the reflected shock zone by time-of-flight mass spectrometry for the H2-D2 exchange measured the time dependence of product formation.10 Recalculation of the single-pulse results93 taking account of nonlinear product growth produced a single Arrhenius line for both sets of data over the temperature range 1000-3000 K. 10 Less work has been reported for heavy atom exchange. A recent study11 confirmed the earlier single-pulse work12 on the self-exchange of carbon monoxide.…”

Section: Introductionmentioning

confidence: 99%

The self-exchange of dinitrogen behind reflected shock waves

Bopp¹,

Kern²,

Niki³

1977

J. Phys. Chem.

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The reaction of an equimolar mixture of 28N2 and 30N2 (4% each) diluted by a mixture of Ne (80%) and Kr (12%) was studied over the temperature and density range 4700-5400 K and 2.5-2. X 10"6 mol cm"3, respectively. The reflected shock zone was sampled by a time-of-flight mass spectrometer at 20-µ8 intervals during typical observation periods of 0.5 ms. The product profiles were fit to the equation (1 -2/29) = exp(-fc'tz), where /29 is the mole fraction of 29N2. The time dependence z was determined to be 2.7 and the rate constants were best represented by the expression k = iO"1,24±0•54 exp(-138 ± 10/RT) µß"2•7. The inert gas dependence was assumed to be first order as reported from a previous single-pulse shock tube investigation. The rate constants from the single-pulse study were recalculated using z = 2.7 and were combined with the results herein. The resulting Arrhenius parameters span the extended temperature range 3200-5400 K: log A = 20.66 ± 0.08; E = 140 ± 1 kcal mol'1. The units of A are cm3 mol"1 s"2,7. The nonlinear time dependence for product formation confirms the earlier proposition of a mechanism which consists of a multistep sequence of reactions.

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Rate of exchange of hydrogen and deuterium behind reflected shock waves. Dynamic analysis by time-of-flight mass spectrometry

Cited by 20 publications

References 1 publication

Dynamic sampling of the deuterium hydride self-exchange behind reflected shock waves

Dynamic sampling of the deuterium hydride self-exchange behind reflected shock waves

Are theD_m_hSymmetric H_x^qRings with 4n+ 2 σ-Electrons and Hydrogen Clusters Aromatic?

The self-exchange of dinitrogen behind reflected shock waves

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Rate of exchange of hydrogen and deuterium behind reflected shock waves. Dynamic analysis by time-of-flight mass spectrometry

Cited by 20 publications

References 1 publication

Dynamic sampling of the deuterium hydride self-exchange behind reflected shock waves

Dynamic sampling of the deuterium hydride self-exchange behind reflected shock waves

Are theDmhSymmetric HxqRings with 4n+ 2 σ-Electrons and Hydrogen Clusters Aromatic?

The self-exchange of dinitrogen behind reflected shock waves

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Are theD_m_hSymmetric H_x^qRings with 4n+ 2 σ-Electrons and Hydrogen Clusters Aromatic?