question_answer 19)

In a reaction between A and B, the initial rate of reaction was measured for different initial concentrations of A and B as given below :  

A/M	0.20	0.20	0.40
B/M	0.30	0.10	0.05

  What is the order of reaction with respect to A and B?

Answer:

 

	Experiment I	Experiment II	Experiment III
A/M	0.20	0.20	0.40
B/M	0.30	0.10	0.05

From experiment I and II, keeping conc. of A constant and that of B is reduced to one third, rate remains the same. This means r = k [B]0                                                                                              ?.. (i) Now let the rate equation is r = k [A]x [B]y                                                      ... (2) From expt. II 5.07 07 x 10?5 = k [0.20]x [0.10]y                 ...(3) From expt. III 1.43 x 10?4 = k [0.40]x [0.05]y                        ...(4) Divide (4) by (3) 2.85 = 2x × [0.5]y Put y = 0 [from eqn. (1)] 2x = 2.8 or 2x = (2)3/2                      i.e., x =   Hence, the rate equation is r = k [A]3/2 [B]0