Question

The order of the reaction is decided by

• A. Pressure
• B. Temperature
• C. Molecularity
• D. Mechanism of reaction as well as the relative concentration of reactants

Answer 1

The correct option is D

Mechanism of reaction as well as the relative concentration of reactants

Explanation for correct option

(D) Mechanism of reaction as well as the relative concentration of reactants

Order of reaction

• “The order of a reaction with respect to a reactant is the power of its concentration which appears in the rate law equation. ”
• “The order of a reaction is the sum of all such powers of concentration of terms for different reactants.”
• The total power of the reactants on the slowest path determines the order of reaction in the case of a complicated reaction.

Explanation for incorrect option

• The order of the reaction is independent of temperature and pressure.
• “Molecularity is defined only for an elementary reaction. Its values are limited from 1 to 3 whereas the order can be 0, 1, 2, 3 or even a fraction.”
• The Molecularity and order of an elementary reaction are the same
• So, the order of the reaction does not depend on molecularity.
• Hence, options (A), (B), and (C) are incorrect.

Hence, option (D) is correct. The order of the reaction is decided by the mechanism of reaction as well as the relative concentration of reactants.