Question

Order of a reaction is ____

(a) Number of molecules of reactants taking part in the reaction

(b) Power of any one of the reactant concentrations

(c) Concentration of intermediate species formed

(d) Sum of the powers of the concentrations of all the reactants

I had been asked this question during an interview.

My question is based upon Reaction Rates topic in chapter Basic Concepts of Chemical Reaction Engineering

Answer 1

Correct choice is (d) Sum of the powers of the concentrations of all the reactants

To elaborate: The order of a reaction with respect to a given substance is the power to which its concentration term is raised in the rate equation. If there is more than one reactant molecules involved in the reaction, then the order of the reaction is the sum of the powers of concentrations of all reacting species in the rate expression.