Consider the decomposition reaction of N_2 O_5 2N_2 O_5 rightarrow 4NO_2 + O_2 A
ID: 989526 • Letter: C
Question
Consider the decomposition reaction of N_2 O_5 2N_2 O_5 rightarrow 4NO_2 + O_2 A proposed mechanism for this reaction is N_2O_5 N O_2 + NO_3 NO_2 + NO_3 rightarrow NO + NO_2 + O_2 NO_3 + NO rightarrow 2NO_2 Assume that the steady-state approximation applies to both the NO and NO_3 reaction intermediates to show that this mechanism is consistent with the experimentally observed rate law d[O_2]/dt = K_obs[N_2 O_5] Express k_obs in terms of the rate constants for the individual steps of the reaction mechanism.Explanation / Answer
let the forward rate constant for 1st reaction is kf and backward rate constant be kb
Then forward rate = backward rate
kf[N2O5] = Kb [NO2][NO3]
[NO2][NO3] = (kf/kb) * [N2O5]
let rate constant of 1nd reaction be k2
Then,
d[O2]/dt = k2 *[NO2][NO3] from 2nd given equation
substitute value of [NO2][NO3] from above
d[O2]/dt = k2 *[NO2][NO3]
d[O2]/dt = k2 *(kf/kb) * [N2O5]
So,
Kobs = k2*kf/kb