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Unformatted text preview: Chemistry 2080 Spring 2010 ANSWERS to Problem Set #4 - due date: Friday February 26th at 2 pm Name:________________ Lab TA Name:__________________ Lab Day/Time:______________________ 1) If you want to get an idea of the rate of a reaction that is extraordinarily slow at room temperature, one thing that you can do is to raise the temperature, measure several rates, and then extrapolate to room temperature. As an example of a slow reaction, at room temperature, hydroxide reacts so slowly with a simple phosphate diester (e.g. dimethyl phosphate) that the hydroxide reacts more rapidly with pyrex glass than it does with the phosphate ester. Listed below are some rate constants that were collected at elevated temperatures. Please calculate the energy of activation (E a ) and the pre-exponential factor (the frequency factor, A) from these data, and then calculate the likely rate constant for the same reaction at 25.00°C. (Either use all four data points in a linear fit - best done on a computer or graphing calculator - or calculate three independent values of E a and A from three pairs of rate constants, and then average the results. Say which method you use). Temperature °C Rate constant (L/mol.sec) 195.0 2.041 x 10-7 215.0 8.891 x 10-7 235.0 3.462 x 10-6 255.0 1.214 x 10-5 ______________________________________________________________________________________...
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This note was uploaded on 03/13/2010 for the course CHEM 2080 taught by Professor Davis,f during the Spring '07 term at Cornell University (Engineering School).
- Spring '07