Question

Choose the correct option(s) regarding order and molecularity:

• A. Molecularity for a particular reaction can be fractional
• B. Order for a particular reaction can be fractional
• C. Molecularity is defined for elementary reactions only.
• D. Order of a reaction is a theoretical value.

Answer 1

Answer: (B), (C)

Molecularity is defined for elementary reactions only.

Comparison Between Order and Molecularity

	Molecularity of Reaction	Order of Reaction
1	It is defined as the no. of molecules of reactant taking part in a chemical reaction.	It is defined as the sum of the power of concentration terms that appear in rate law.
2	It is always a whole number. It can neither be zero nor fractional.	It may be zero, fractional or integer.
3	It is defined only for elementary reactions.	It is defined for elementary as well as complex reactions.
4	It is a theoretical value.	It is an experimental value.