In a reaction if the concentration of reactant A is tripled, the rate of reaction becomes twenty-seven times. What is the order of the reaction?


 

The rate of any elementary reaction can be represented as

r=k[A]n

After changing concentration to its triple value A = 3A, r becomes 27

27r=k[3A]nr27r=k[A]nk[3A]n127=[13]n[13]3=[13]n

Hence, n= 3
The order of the reaction is three.