The temperature dependence of the rate constant for the reaction of hydroxyl radicals With nitric acid

Abstract

The flash photolysis resonance fluorescence technique has been used to measure the rate constant for the reaction products over the temperature range 225–443 K. The data below room temperature can be fit to the expression k1 = (1.05±0.40) × 1014 exp [(759±100)/T] cm3 molec−1 S−1. This equation, however, markedly underestimates the values of k1 above 300 K. An interpretation of the behavior is presented, and implications of these values for k1 on stratospheric reaction cycles are discussed.

Kinetics of the reaction of OH with pernitric and nitric acids

“…Our OH + HN03 results are in very good agreement with those reported in the recent flash photolysis studies of Wine et al [5], Kurylo et al (61,Margitan and Watson [7], and Marinelli and Johnston [ 8 ] , and with the discharge-flow study of Jourdain et al [9], all of which show a pronounced increase in ke at low temperatures. Some of these investigators [6,7] report a curved Arrhenius plot, that is, a leveling off in k:, above room temperature, but our own data do not span a sufficiently wide temperature range to support this observation. The discrepancy with the discharge-flow study of Connell and Howard [lo] remains unexplained.…”

Reactions of OH radicals with inorganic compounds in the gas phase

“…At room temperature the reported absolute rate constants can be grouped around two values, 5.2 x 101° and 8.0 x 101°, with no adequate explanation for the difference. Temperature dependence studies [133,[136][137][138][139][140][141][142]144], although not in complete agreement at room temperature, give a negative activation energy of about -1.5 kcal/mol. The question of a pressure effect on the rate constant is also not completely resolved, and even two studies from the same laboratory are in conflict.…”

OH reaction rate constant, IR absorption spectrum, ozone depletion potentials and global warming potentials of 2-bromo-3,3,3-trifluoropropene

“…General descriptions of the apparatus and the experimental method used to measure the OH reaction rate constants are given in previous papers [ Kurylo et al , 1982; Orkin et al , 1996]. In the present work we used the same principal configuration of the apparatus with a number of modifications made to improve the accuracy of the obtained kinetic data by decreasing and quantifying the instrumental uncertainties.…”