What is the order of reaction and how does it relate to rate equations?

The order of reaction describes how the rate of a reaction changes with respect to the concentration of reactants.

The rate equation of a reaction shows the relationship between the rate of the reaction and the concentrations of the reactants. The order of reaction is determined by the sum of the powers to which the concentrations of the reactants are raised in the rate equation. For example, if the rate equation is rate = k[A]^2[B], the order of reaction with respect to A is 2 and with respect to B is 1, giving an overall order of 3.

The order of reaction can also be determined experimentally by measuring the rate of the reaction at different concentrations of the reactants. If the rate of the reaction doubles when the concentration of a reactant is doubled, the reaction is said to be first order with respect to that reactant. If the rate of the reaction quadruples when the concentration of a reactant is doubled, the reaction is said to be second order with respect to that reactant. If the rate of the reaction remains constant when the concentration of a reactant is doubled, the reaction is said to be zero order with respect to that reactant.

Knowing the order of reaction is important for understanding the mechanism of a reaction and for predicting how changing the concentration of reactants will affect the rate of the reaction.