"A complex reaction consists of a number of steps. The overall rate of the reaction depends on the' slowest step" Illustrate the above statement with ąn example and also mention the mechanism.

Explanation

Slowest step is called the rate determining step. So it can decide the overall rate of a complex reaction. Eg: Thermal decomposition of `(N_(2) (O)_(5)` The chemical equation is `2 (N)_(2) (O)_(5) rarr 4 (NO)_(2)+(O)_(2)`
But `(r)=(k)[(N)(O)_(5)] therefore It is a first order reaction
The mechanism is `(N)_(2) (O)_(5)^(2) rarr(slow)(NO)_(2)+(NO)_(3)`
(Slowest step-rate determining step)
`(N)_(2) (O)_(5)+(NO)_(3)rarr(fast) 3 (NO)_(2)+(O)_(2)`