For the reaction A + B → products, it is observed that
(i) On doubling the concentration of A only, the rate of reaction is also doubled.
(ii) On doubling the initial concentration of both A and B, there is change by a factor of 8 in the rate of reaction.
The rate of reaction is given by
rate = k [A] [B]
rate = k [A]2 [B]
rate = k [A] [B]2
rate = k [A]2 [B]2