Reaction of hydrogen with nitric oxide

Early investigations of the reaction between hydrogen and nitric oxide in the temperature range 970—1100 K were made by Hinshelwood and Green [300] and Hinshelwood and Mitchell [301], who followed the pressure decrease in a static system. The observed order was somewhat variable, but they concluded that the reaction was essentially third order — second order in NO and first order in H2. Later studies were by Graven [302], and Kaufman and Decker [303]. Graven studied the reaction in a 

Kaufman and Decker [303] considered the rate controlling step in the reaction to be the reduction of NO to N2O, after which the more rapid steps associated with the propagation mechanism in the H2 + N2O system could take place. The mechanism has been further investigated by Wilde [299] using computer modelling techniques. The principal elementary steps contributing to the first stage, i.e. the removal of NO, are probably reactions (—xxix), (xxviii), (xlvii) and (i), with contributions also from reaction (xlvi) and the forward reaction (xxix), viz. 

Omitting reaction (xlvi), a conventional steady state treatment, with reactions (xxviii) and (xxxix) equilibrated, leads to 

This approximates to the overall orders in NO and H2 observed under some conditions. By including reaction (xlvi) with, somewhat arbitrarily, fe4 6 = 3 X 10 exp (—1750/T), Wilde [299] found slightly greater than one half order in H2. For the temperature range 1100—1360 K, the mean value of kn 7 giving the best overall agreement with experiment was = 2 X 10 exp (—13,000/T), to within a factor of two (cf. analysis of H2 + N2O system by Baldwin et al. [297] in Sect. 8.4.1). 

Attempts at computer simulation of the observed shock tube data in the initial stages of the reaction have led in all the investigations [304—307] to the conclusion that the rate-determining step at temperatures above 2400 K is reaction (xlviii) and it is worthy of note that Magnus et al. [308] have also concluded that reaction (xlviii) is important in H2 + NO flames at similar temperatures (cf. earlier conclusions of Adams et al. [284]). The principal steps in the initial stages of the shock tube combustion are thus likely to be 

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The reaction of hydrogen with nitric oxide produces a red emission corresponding to, "" ... 

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