By using following mechanism determine the order of the reaction ( i ) A 2 → A + A (fast) i i A + B 2 → A B + B (slow) ( i i i ) A + B → (fast)

Step-by-step solution

Slowest step is rate determining step, hence the rate will be given by slowest step. Thus r = K [ A ] [ B 2 ] . Where [ A ] is intermediate, which is derived from K c = [ A ] [ A ] [ A 2 ] or [ A ] = [ K c ] 1 / 2 [ A 2 ] 1 / 2 r = K × [ K c ] 1 / 2 [ A 2 ] 1 / 2 [ B 2 ] = K [ A 2 ] 1 / 2 [ B ] . Thus, order is 0.5 + 1 = 1.5