Question

define order of reaction

Answer 1

The sum of concentration terms on which the rate of a reaction actually depends as observed experimentally iscalled the order of the reaction i.e. the sum of the powers or exponents to which the concentration or pressure terms are raised in order to determine the rate of the reaction.

Answer 2

the sum of the powers or exponents to which the concentration or pressure terms are raised in order to determine the rate of the reaction.

Order of a reaction is an experimental quantity. A reaction is said to be of the zero order, first order, second order, and third order if some of concentration terms is equal to 0, 1, 2 and 3 respectively.