Problem Set 6

1. The acid hydrolysis of sucrose into glucose and fructose is a first order reaction in terms of sucrose concentration.

a. Write the rate law for this reaction.

b. Laboratory experiments revealed that the rate constant for this reaction was 7.8 x 10^-3 sec^-1 at a temperature of 28°C and was 3.2 x 10^-2 sec^-1 at 40°C. Calculate the activation energy for this reaction.

c. Determine the value of the rate constant k at a temperature of 37°C.

d. For each of the two temperatures above, use your calculated activation energy to determine the fraction of molecular collisions with sufficient kinetic energy to react.

e. Calculate the collision frequency factor A for a temperature of 40°C.

2. Experiments were conducted in order to determine the rate law for the reaction between two substances X and Y:

Experiment	[X]	[Y]	Initial rate (M/sec)
1	1.25 x 10-3 M	1.25 x 10-3 M	0.0087
2	2.50 x 10-3 M	1.25 x 10-3 M	0.0174
3	1.25 x 10-3 M	3.02 x 10-3 M	0.0508

a. Determine the rate law for this reaction by finding the order with respect to each reactant and the overall reaction order.

b. Determine the value of the rate constant k for this reaction.

c. Predict the initial rate of reaction for reactant concentrations of 1.0 mM in X and 5.0 mM in Y.

3. Outline and fully explain the graphical procedures that you would use to determine whether a specific reaction were first or second order with respect to reactant A.

4. The elimination of drugs from the bloodstream is generally a first order process; i.e. the rate of drug elimination is directly proportional to the serum drug concentration. Fluvoxamine was one of the first selective serotonin reuptake inhibitors (SSRI’s) developed to treat depression. Recent NMR experiments have revealed that the half-life of fluvoxamine in the brain is approximately 58 hours. Determine the fraction of fluvoxamine remaining in the patient’s brain one week after cessation of treatment.