Dwayne Bolton

Chemistry

11 March, 11:45

Your laboratory is asked to analyze a water sample for a particular pesticide. You know from the previous study that this pesticide degrades via a first-order, irreversible reaction. The first-order rate constant (k) for the reaction at 4 °C is 0.02 daył. The activation energy for the reaction is known to be 10 kcal/mol. The standard preservation method for water samples containing this pesticide is to store the sample at 4 °C for no more than 24 hours prior to analysis. a. Calculate the fraction of the pesticide that remains in the sample after 24 hours of storage at 4 °C.

b. A newly hired staff member does not know the proper procedures and, after taking a sample of the water, forgets to store it at 4 °C. Instead, he leaves the sample in the trunk of his car (average temperature 35 °C) over the weekend. 60 hours later the sample is analyzed and found to contain 0.01 mg/L of the pesticide. What was the pesticide concentration in the water at the time the sample was taken?