Question

For this important smog reaction the experimental rate law is r=kexp [NO]^2[O2]. a.) Show that the following mechanism is consistent with the rate law and identify keep proposed mechanism. NO+NO<--> N2O2 fast k1/k-1 N2O2+O--> 2 NO2 slow k2
b.) What is the function of N2O2 and how do you know?
c.)What is the difference between a catalyst and an intermediate ?
d.) Activation energies are: 82(r1), 205(r-1, and 82(r2) kJ/mol. If the Arrhenius pre-exponential factors all approximately the same what happens to the overall rate as the temperature is increased?
What is d saying?

Answer 1

The reaction is an example of complicated reaction

The reaction will be

2NO + O2 --> 2NO2

The mechanism is

NO+NO<--> N2O2 fast k1/k-1

N2O2+O--> 2 NO2 slow k2

We will use equilibrium approximation to solve the same

[The rate of forward reaction = rate of backward reaction]

a)

b) N2O2 is an intermediate as it is not involved in the rate law expression.

c) The catalyst is added during the reaction to alter the pathway of the reaction and hence alter the rate ofreaction, however the intemediate is formed in the reaction itself. It does not affect the rate of reaction .

d) The activation energy of the given system will be negative

As activation energy of forward reactions = 82 + 82 = 164

While of backward reaction = 205 Greater then above.

So this indicates that the Overall rate of reaction will decreases with increase in temperature.

This suggest that the rate constant will decrease with increase in tempearture