The hypothetical reaction A B 2AB; → follows the following mechanism Fast A A A, → Slow Fast A B AB B,A B AB. → → The order of the overall reaction is

From slow step, rate 2 k B A From 1st equation 2 eq 2 A K A Or 1/2 1/2 eq 2 eq 2 A K A K A Hence, rate 1/2 1/2 2 eq 2 k B K A 1/2 2 2 k ' A B Hence, order 1 3 12 2