The Kinetics of the Nitrogen Dioxide-Hydrogen Chloride Reaction

Abstract

These reactions are catalyzed by HN03 and H20 through heterogeneous reaction paths having negative temperature dependences. The active reaction sites in these heterogeneous paths appear to be HN03 dimers and polymers which are hydrated in the presence of H20. Only the first reaction with an equilibrium constant of 645 ± 79 (atm units) at 25 °C has an appreciable homogeneous rate that is second order in N02 and first order in HCI. The experimental rate equations for these reactions, their temperature dependences, and reaction mechanisms are presented.

The Reaction of Dinitrogen Pentoxide with Hydrogen Chloride

“…7,8, and 9 where the HC1 pressures were 34.8 Torr, 75.1 Torr, and 172.6 Torr, the slopes gave, respectively, fourth-order rate constants of 4.5 X 10s M-3 s-1, 3.4 X 10® M-3 s_1, and 2.9 X 10® M-3 s_1, all of which were smaller than the value of 1.9 X 109 M-3 s_1 obtained from Figure 2. Although our data were not sufficient to deduce independently the rate term for this additional (HC1) dependence, kinetic studies (Kuo et al, 1976) of other reactions between HC1 and nitrogen oxides suggested the form of this dependence to be as shown by the second term in eq 4. Figure 2.…”

“…Rate equations representing nitric acid catalysis in other reactions of nitrogen oxides and oxyhalides were found to be associated with heterogeneous mechanisms (Kuo et al, 1976; Wilkins, 1973), and we make a similar interpretation of the rate eq 4 even though we were unable to examine the temperature dependence of reaction 3 nor its dependence on the surface to volume ratios. The thermal instabilities of the reactants and products, the occurrence of additional side reactions, and the rates becoming too fast for our instruments prevented us from carrying out these additional studies.…”

“…Since catalysis by HNO3 appeared to be a fairly common phenomenon among the reactions (Kuo et al, 1976;Wilkins, 1973) of nitrogen oxides and oxyhalides, it was very probable that reaction 1 was also affected by this acid. This expectation was verified by a single kinetic run we made at 25 °C using the same Pyrex glass infrared absorption cell.…”

“…The Pyrex glass infrared absorption cell (S/V = 1.2 cm-1) which served as the reaction vessel and the general experimental procedure used here were identical to those employed in the kinetic studies of N02-HC1 reaction (Kuo et al, 1976).…”

The etching behavior of n-GaP in aqua regia solutions

“…The reaction between HCl and HNO 3 in aqueous solutions has been reported to be which consists of two separate sequential reactions, [15] HCl þ HNO 3 …”