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Kinetics of the Depolymerization of Diacetone Alcohol Essay

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Experiment N | Kinetics of the Depolymerization of Diacetone Alcohol via Basic Catalysis | | Ingrid Tafur -5672578 | 2/11/2011 |

CHM233O
Partner: Laura Marrongelli
Demonstrator: Cheryl McDowall

Objective
The rate constant of the depolymerization of diacetone alcohol via basic catalysis was determined by monitoring the change in volume as a function of time at constant temperature of a pseudo first order reaction where the species in excess was sodium hydroxide. This was accomplished by using a dilatometer as the apparatus and following both methods: isolation and initial rates in conjunction.
Introduction
Depolymerization is the process in which a compound is converted into one of a smaller molecular weight and of …show more content…

This increases the volume density. The volume of one molecule of diacetone alcohol is not the same as the effective volume of two molecules of acetone. Recall, that the rate constant is temperature dependent. Thus, the temperature must remain constant. The reagents and reaction occur submerged in a thermal water bath at 27C.

Figure 1 : The apparatus a dilatometer submerged in a constant water temperature at 27C.

As a result of volume being directly proportional to concentration, equation four becomes ln⁡(vt- v∞)=-kobst ⁡ (5)
Where v∞ is the volume at infinity, which is related to the starting amount of reagent. It is found when the reaction goes to completion and plateaus. vt is the volume at each reading from the dilatometer.
To find the rate constant of the reaction, the logarithm is taken for both sides of the equation in equation 3. This is known as the method of initial rates, the rate is measured at the beginning of the reaction for several different initial concentrationsii. log⁡(kabs)=logk+mlog[OH-] (6)

In order to determine the rate constant ‘k’, three different hydroxyl-dependent observable k are needed and so a solution of NaOH must be made from the standard solutions given. To precisely know the concentration of the new molar NaOH concentration, a back titration standardization must be performed. To calculate the new molar

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