The reaction A2 + B2 → 2AB occurs in following steps: A2 → A + A   (slow) A + B2 → AB + B   (fast) A + B → AB    (fast) What is the order of the reaction?

\(\frac{3}{2}\) 2 0 1

1

Slowest step of mechanism is the rate determining step. A2 → A + A   (slow) r = k [A2]1  This is a first order reaction.