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Direct measurements of the reactions NH/sub 2/ + H/sub 2/ in equilibrium NH/sub 2/ + H at temperatures from 670 to 1000 K

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100402a048· OSTI ID:5630214
The reactions NH/sub 2/ + H/sub 2/ ..-->.. NH/sub 2/ + H (1) and H + NH/sub 3/ ..-->.. NH/sub 2/ + H/sub 2/ (-1) were studied in a discharge flow system in the temperature range 673 less than or equal to T/K less than or equal to 1003 at a pressure of 4 mbar with He as the main carrier gas. Pseudo-first-order conditions (H/sub 2/)/sub 0/ >> (NH/sub 2/)/sub 0/ and (NH/sub 3/)/sub 0/ >> (H)/sub 0/ were applied when (NH/sub 2/)(t) (followed by LIF) and (H)(t) (followed by Lyman-..cap alpha.. absorption), respectively, were measured. The rate constants are presented by the Arrhenius expressions k/sub 1/(T) = 3.6 x 10/sup 12/ exp(-(38 +- 3) kJ mol/sup -1//RT) cm/sup 3/ mol/sup -1/ s/sup -1/ and k/sub -1/(T) = 8.1 x 10/sup 13/ exp(-(60.9 +- 4) kJ mol/sup -1//RT) cm/sup 3/ mol/sup -1/ s/sup -1/. From the ratio k/sub 1/(T)/k/sub -1/(T) the NH/sub 2/ enthalpy of formation ..delta..H/sub f//sup 0/(298 K) = 192 kJ mol/sup -1/ at room temperature is determined.
Research Organization:
Max-Planck-Institut fuer Stroemungsforschung, Goettingen, West Germany
OSTI ID:
5630214
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:11; ISSN JPCHA
Country of Publication:
United States
Language:
English