Nucleophilic Prostitution

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Abstract The focus of this experiment was to analyze the kinetics of a nucleophilic substitution. A mixture of 0.3622-M 1-bromopropane and 0.3622-M potassium hydroxide in an 90:10 ethanol/water solvent provided the reactants for a SN2 reaction to occur in a temperature controlled bath at 50.0˚C. The disappearing reactant was found by titrating timed aliquots during the reaction and then measuring the concentration of hydroxide. The k-value was found to be 0.0202 M-1Min-1. Using the linear form of the Arrhenius equation the activation energy was calculated to be 19.9 kcal/mol. By looking at the 1/ [OH] vs. time graph, it is made clear that this is a SN2 reaction with second order kinetics because it derived from a second order rate equation…show more content…
Using another 125-mL flask, 60-mL of 0.3622 M potassium hydroxide in ethanol was deposited. Both flasks were clamped in a temperature-controlled bath regulated at 50.0˚C. The solutions were then set in the temperature bath for ten minutes to equilibrate. An empty 250-mL Erlenmeyer flask was also clamped in the same water bath. In another flask 50-mL of ice water was deposited with three-drop phenolphthalein. Using a volumetric pipet 50-mL of the 1-bromopropane was added into the empty flask in the bath. By the same method 50-mL of potassium hydroxide was delivered to the same flask while swirling the contents and remaining in the water bath. A 10-mL aliquot was immediately removed from the mixture and added to the ice water containing the phenolphthalein. When the pipet was half emptied into the ice water a timer was started. This aliquot was the first sample taken at t=0. The sample was rapidly titrated with 0.100 M HCl to a phenolphthalein endpoint and the final volume was…show more content…
You can position the text box anywhere in the document. Use the Drawing Tools tab to change the formatting of the pull quote text box.] [Type a quote from the document or the summary of an interesting point. You can position the text box anywhere in the document. Use the Drawing Tools tab to change the formatting of the pull quote text box.] Table [ 1 ] Progression of Substitution Reaction Time (min) | Vol. 0.1 M HCl | Moles of HCl | Moles NaOH in aliquot | Volume of aliquot (L) | [NaOH] (M) in aliquot | 1/[NaOH] (M-1) | 0.00 | 18.59 | 0.00186 | 0.00186 | 0.01 | 0.186 | 5.376 | 20.03 | 16.99 | 0.00170 | 0.00170 | 0.01 | 0.170 | 5.882 | 35.01 | 17.28 | 0.00173 | 0.00173 | 0.01 | 0.173 | 5.780 | 49.39 | 15.33 | 0.00153 | 0.00153 | 0.01 | 0.153 | 6.536 | 64.43 | 15.51 | 0.00155 | 0.00155 | 0.01 | 0.155 | 6.452 | 74.36 | 14.22 | 0.00142 | 0.00142 | 0.01 | 0.142 | 7.042

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