question_answer 20)

The following results have been obtained during the kinetic studies of the reaction : 2A + B  C + D

Experiement	[A]M	[B]M	Initial rate of formation of
I	0.1	0.1
II	0.3	0.2
III	0.3	0.4
IV	0.4	0.1

  Determine the rate law and the rate constant for the reaction.  

Answer:

From experiments II and III, it is clear that keeping conc. of A constant and that of B is doubled, the rate of reaction becomes four times. Thus, order w.r.t. B is 2 (r  [B]2). From experiments I and IV, keeping conc. of B constant and that of A is quadrupled. The rate of reaction becomes four times. Thus, order w.r.t. A is 1 (r  [A]1). Hence, rate law is   r = k [A]1 [B]2. Order = 1 + 2 = 3 Rate constant can be found from any of the experiment. From experiment I,