At the lowest temperatures the reaction NH2+N2H,--->N2H,+NH, appears to become important.From the experimental concentrations, a value of ka = 2.5 X 10 13 cc/mole-sec (2000 0 K) is obtained. An order-of-magnitude estimate gives k,,,-,10 1 ' cc/mole-sec (20000K).
Chemically activated sec-butyl radicals have been produced at temperatures between -103° and 25°C by reaction of H atoms with cis-butene-2. H atoms were allowed to effuse through a molecular slit into a spherical reactor containing olefine at low pressure. The system resembles the Polanyi diffusion flame, and some solutions for the radial distribution functions of the species involved are given. Disproportionationrecombination ratios for sec-butyl radicals, and for methyl plus butyl radicals, were measured as 0.94 and 0.30 respectively. The ratios of stabilization vs decomposition by C-C rupture for the energized butyl radicals were measured as a function of pressure and temperature. Hydrogen and helium were also used as inert gases. ka the observed rate constant for decomposition is ",10 7 sec-I. The energized butyl radicals are closely monoenergetic. The unimolecular decomposition behavior is compared with theory wherein expressions due to Marcus are employed. All vibrational degrees of freedom may be taken as active.
The coupling of a shock tube to a time-of-flight mass spectrometer for the determination of kinetic data is described whereby analysis is performed every 25 μsec. The rate of dissociation of Cl2 has been measured over the temperature range 1700°—3200°K under essentially isothermal and isobaric conditions with the observed rate constants in fair agreement with those obtained by the spectroscopic technique. The observed temperature dependence is less than predicted by simple collision theory with an apparent activation energy of 41±5 kcal/mole.
part upon the stabilities of the saturated solutions, doAcknowledgments. The preliminary experimental indeed decrease markedly as the atomic number of the work carried out by J. Daniel, A. Leenstra, D. Leenstra, alkali metal increases. The reported dichromate soluand R. Blankespoor is acknowledged with thanks. bilities at 20" (in some cases interpolated or extrapolated from other temperatures) are, in molalities : Li+, 5.37;25 Na+, 6.78; K+, 0.41; Rb+, 0.18;26 Cs+, 0.060. 27 Work in progress includes a study of the behavior of electrolytes in systems containing high surface area carbonaceous materials.The rate of the exothermic free-radical reaction NF2 + Fz 3 NF3 + F has been directly determined by measuring the disappearance of molecular fluorine and the initial rate of NF3 formation in the temperature range 1100-1600°K by means of a shock tube coupled to a TOF mass spectrometer. (-14,40O/RT) M-' sec-l is obtained for the rate constant which when extrapolated (-107) to near room temperature is in reasonable agreement with the data (corrected) of Levy and Copeland2 although the activation energy is -5 kcal/mole higher. The dissociation of fluorine in neon was also studied in the temperature range 1400-2000°K where k~~ = 2.0 X 10' 0 exp( -35,00O/RT) M-' sec-l is an Arrhenius fit to the data.The Arrhenius expression k, = 4.8 X l O Q exp
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