rate = K[R1][R2] Order of the reaction is the sum of the powers of the concentration terms of the reactants in the rate expression. So order = 1+1 = 2 ---> 2nd order reaction Solution rate = K[R1][R2] Order of the reaction is the sum of the powers of the concentration terms of the reactants in the rate expression. So order = 1+1 = 2 ---> 2nd order reaction.