The kinetics of the reaction between two substances, A and B, was investigated u

Question

The kinetics of the reaction between two substances, A and B, was investigated using the method of initial rates in a series of three experiments.

In the first experiment, the initial concentration of A was 0.200 mol L-1, the initial concentration of B was 0.800 mol L-1, and the rate of the reaction was observed to be 1.39 mol L-1 of product per minute.

In the second experiment, the concentration of A was kept the same (0.200 mol L-1), and the concentration of B was doubled to 1.60 mol L-1. In this experiment, the rate was observed to be 2.78 mol L-1 of product per minute.

In the third and last experiment, the concentration of B was kept the same as in the second experiment (1.60 mol L-1), and the concentration of A was tripled to 0.600 mol L-1. In this experiment, the rate was observed to be 8.34 mol L-1 of product per minute.

The order with respect to A =

The order with respect to B =

The overall order =

show all work please

Explanation / Answer

Let the reaction be of order n wrt A.

r=k[A]n

Keeping [B] constant:

Taking experiment 2 and 3:

r2=k[0.200]n=2.78 ..(1)

r3=k[0.600]n=8.34 ..(2)

Dividing 1 by 2:

(0.200/0.600)n=2.78/8.34

(1/3)n=1/3

n=1

Thus reaction is 1st order wrt A.

Keeping [A] constant:

Taking experiment 1 and 2:

r2=k[0.800]n=1.39 ..(3)

r3=k[1.60]n=2.78 ..(4)

Dividing 3 by 4:

(0.800/1.600)n=1.39/2.78

(1/2)n=1/2

n=1

Thus reaction is 1st order wrt B.

Overall order= order wrt A+ order wrt B

=1+1=2

Thus it is 2nd order overall.

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