(solution) A compound A undergoes a first-order decomposition reaction at

(solution) A compound A undergoes a first-order decomposition reaction at

 A compound A undergoes a first-order decomposition reaction at 320K. An

investigator conducts experiments that yield the following concentration data for A as a

function of time:

Time (min.) 0 8.42105 25.26316 42.10526 63.15789 80

[A](mmol L

-1

) 10.0 9.34851 8.17009 7.14022 6.03347 5.2729

Time (min.) 92 112 120 132 160 200

[A](mmol L

-1

) 4.479 3.41229 3.06052 2.13423 0.92034 0.2767

Without the investigator?s knowledge, a practical joker alters the reaction temperature to

340 K partway into the experiment. At a later time, this same joker raises the temperature

again. The investigator cannot understand his data and concludes that his apparatus must

have a serious design flaw. He needs your assistance.

(A)

Determine the time at which the practical joker altered the temperature to 340K

and the time at which he raised the temperature second time.

(B)

Determine the reaction rate constant for the decomposition at 320K