Nitric Oxide. NO reacts with oxygen to produce nitrogen dioxide.
2NO(g) + O2(g) → 2NO2(g)
The rate law for this reaction is
rate = k[NO]2 [O2]
Propose a mechanism for the above reaction.
Rate of the reaction depends upon the slowest step of the elementary processes.
NO + O2 → NO3 (fast) ...(i)
NO3 + NO → NO2 + NO2 (slow) ...(ii)
Rate law is: Rate k[NO3] [NO] but NO3 is essentially NO + O2
So, rate = k[NO]2 [O2].
This reaction follows second order kinetics.
So that, the rate equation for this reaction will
Rate, R = k[X]2 .............(1)
Let initial concentration is x mol L−1,
Plug the value in equation (1)
Rate, R1 = k .(a)2
Given that concentration is increasing by 3 times so new concentration will 3a mol L−1
Plug the value in equation (1) we get
Rate, R2 = k (3a)2
We have already get that R1 = ka2 plus this value we get
R2 = 9 R1
So that, the rate of formation will increase by 9 times.
Rate = k[A]2
If concentration of X is increased to three times,
Rate = k[3A]2
or Rate = 9 k A2
Thus, rate will increase 9 times.