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***MUST SHOW WORK FOR POINTS*** The kinetics of the reaction between two substan

ID: 839970 • Letter: #

Question

***MUST SHOW WORK FOR POINTS***

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 0.400 mol L-1, the initial concentration of B was 0.600 mol L-1, and the rate of the reaction was observed to be 1.05 mol L-1 of product per minute.

In the second experiment, the concentration of A was kept the same (0.400 mol L-1), and the concentration of B was doubled to 1.20 mol L-1. In this experiment, the rate was observed to be 1.05 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 (1.20 mol L-1), and the concentration of A was tripled to 1.20 mol L-1. In this experiment, the rate was observed to be 9.45 mol L-1 of product per minute.

The order with respect to A =

The order with respect to B =

The overall order =

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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[0.400]n=1.05 ..(1)

r3=k[1.20]n=9.45 ..(2)

Dividing 1 by 2:

(0.400/1.20)n=1.05/9.45

(1/3)n=1/9

n=2

Thus reaction is 2nd order wrt A.

Keeping [A] constant:

Taking experiment 1 and 2:

r2=k[0.600]n=1.05 ..(3)

r3=k[1.20]n=1.05 ..(4)

Dividing 3 by 4:

(0.600/1.20)n=1.05/1.05

(1/2)n=1

n=0

Thus reaction is 0th order wrt B.

Overall order= order wrt A+ order wrt B

=2+0=2

Thus it is 2nd order overall.