A. General Procedure
Repeat the following procedure three times and record the time for 10% reaction, the solvent composition (by volume), and the temperature. Determine the average time and the average deviation in seconds.
1. Pipet 3 mL (5-mL graduated pipet) of a 0.1 M solution of tert-butyl chloride in acetone into a 25-mL Erlenmeyer flask and place the flask on white paper.
2. Pipet 0.3 mL (1-mL graduated pipet) of the 0.1 M sodium hydroxide solution into a second 25-mL flask and then add 6.7 mL of distilled or deionized water (small graduated cylinder or pipet). Add several drops of bromphenol blue indicator solution.
3. Note the time and quickly pour the acetone solution into the water solution, swirl for a second, and immediately pour the solution back into the other flask. (This procedure will insure complete mixing.) Note the time when the indicator changes color. Before beginning each experiment, the two flasks should be rinsed with acetone and drained.
EXERCISES
1. How many millimol (mmol) each of tert-butyl chloride and hydroxide ion are present in each flask prior to mixing?
2. Does the acetone participate directly in the reaction? Does the water participate in the reaction? Explain.
3. The relationship between the rate constant for a unimolecular reaction and the percent reaction is given by the expression
kt = ln 1 / (1 - % reaction/100)
Calculate the value of k (in sec-1) for the data from Part A.