Question

Write any two differences between the order of a reaction and molecularity of a reaction.

Hint:

Order = Experimental sum of powers. Molecularity = Theoretical number of colliding molecules.

Answer 1

Step 1: Concept
Reaction kinetics involves both theoretical mechanisms (molecularity) and experimental rate laws (order).

Step 2: Meaning
Order is the sum of the powers of the concentration terms appearing in the rate law expression. Molecularity is the total number of reacting species participating simultaneously in a single elementary reaction step.

Step 3: Analysis
Because order is derived experimentally, it can be zero or a fraction. Because molecularity counts the physical number of colliding molecules, it must strictly be a positive whole number (e.g., 1, 2, or 3) and cannot be zero or fractional.

Final Answer: 1. Order is an experimentally determined value, while molecularity is a theoretical concept derived from the reaction mechanism. 2. Order can be zero or a fractional value, whereas molecularity can only be a positive whole number (1, 2, 3...).