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Determination of pKa: Effects of Substituents on AcidityFinal Lab ReportBySam Zike Gabe Jones and Dom BozehLab: Thursday 2:50-5:40 PM 2175CHM 25601-009Date: March 30th, 2017Due Date: March 30th, 2017
Purpose of the Experiment:The purpose of this experiment is to determine the pKa of a series of para-substituted benzoic acids to understand how the substituents affect theionization of the acids.Chemical Structures/Reactions:
Calculations: CDEFGHIVpHVIpH/VVII(pH/V)(pH/V)VII2.030.161.020.07882.015-0.0179-0.01Results and Discussion:Results Successful calibration20mg of 4-dimethyl aminobenzoic acid5.16 was the start pH of the solution0.5 mL addition at 15 second intervals23- 0.5 mL addition in the fast run16- additions in slow runslow run was expedited to get to critical drop period fastersolution was clear6mL + (7.2ml-0 x 0.2mL) = 6.105 mL pKa = 4.10(13.6567)Discussion1.The quick run provided a broad parameter of where the spike in pH would occur, it was not as accurate as the slow run as larger amounts were added.