Why molecularity is applicable only for elementary reactions and order is applicable for elementary as well as complex reactions?

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Solution

A complex reaction occurs through a number of steps i.e., elementary reactions. The number of molecules involved in each elementary reaction may be different. i.e., the molecularity of each step may be different. Therefore, it is meaningless to talk of molecularity of the overall complex reaction.

On the other hand, the order of complex reaction depends upon the molecularity of the slowest step. Hence, it is not meaningless to talk about the order of a complex reaction.

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Similar questions

Which of the following statements are applicable to a balanced chemical equation of an elementary reaction?
(a) Order is same as molecularity
(b) Order is less than the molecularity
(c) order is greater than the molecularity
(d) Molecularity can never be zero

Q. Which of the following statements are correct?

(i) Law of mass action and rate law expressions are same for single step reaction.
(ii) Order of the slowest elementary reaction of a complex reaction gives the order of the complex reaction.
(iii) Both order and molecularity have normally a maximum value of 3.
(iv) Molecularity of a complex reaction

A + 2 B \to C

is 3.

Q. For the elementary reaction

A + B \to 2 C

the experiment data suggested that

Rate (r) = k [A] [B]

. The molecularity and order of the reaction are respectively:

Q. Differentiate between Complex reaction and elementary reaction?

Q. What is the rate of reaction for a bimolecular elementary reaction?

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