Passage IV

Acetates are compounds with the chemical formula CH₃CO₂R, where R is an unreactive chain of carbon and hydrogen atoms. In the presence of a catalyst, acetates can undergo hydrolysis (reaction with H₂O) to produce both acetic acid (CH₃CO₂H) and an alcohol (ROH):

The rate at which hydrolysis occurs is proportional to the rate constant, k, of the reaction.

Three experiments were done to determine k for the hydrolysis of various acetates. In each trial, Steps 1-3 were performed:

1. Three mL of aqueous 1.0 mole/liter (mol/L) potassium hydroxide (the catalyst) and 80 mL of a solvent were combined.

2. The solution was brought to a particular temperature, and then 0. 2 mL of an acetate was added to the solution.

3. The progress of the hydrolysis reaction at the particular temperature was monitored over time to determine k, measured in.

Experiment 1

In Trials 1-6, k for each of 6 acetates with different R chains (groups) was determined using a solvent composed of 37% acetone and 63% H₂O, by volume, at 25C. See Table 1.

Experiment 2

In Trials 7-10, Trials 1-4 of Experiment1 were repeated, except with a solvent composed of 70% acetone and 30% H₂O by volume. See Table 2.

Experiment 3

In Trials 11-13, Trial 8 of Experiment 2 was repeated at 3 other temperatures: 20℃, 35℃, and 45°C. In Trials 14-16, Trial 9 was repeated at those 3 temperatures. In Trials 17-19, Trial 10 was repeated at those 3 temperatures. See Table 3.

Tables adapted from S. Hilal, "Estimation of Hydrolysis Rate Constants of Carboxylic Acid Ester and Phosphate Ester Compounds in Aqueous Systems from Molecular Structure by SPARC." U. S. Environmental Protection Agency. 2006.