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Figure 2: Titration of Second Vinegar Sample with Sodium Hydroxide Vinegar Sample 1 Vinegar Sample 2 Vinegar Sample 3 Mass of Vinegar 4.955.14.9Volume of Vinegar Density = 1.005 g/mL 130137135Initial NaOH volume in syringe 89.510.2Final NaOH volume in syringe 22.214.171.124Volume of NaOH Delivered 67.27.8Moles of NaOH Delivered 0.0942M.097 M.095MMoles of Acetic Acid in Sample 0.84M0.84M0.844MMass of Acetic Acid in Sample 2.02 g2.01 g2.01 gCalculated Molarity of Acetic Acid in the sampled vinegar 0.791 M0.789 M0.790 MCalculated Percent Mass of Acetic Acid in sampled vinegar 3.8%3.49%3.71%Average Calculated Percent Mass of Acetic Acid in Sampled Vinegar 3.7%Figure 3: Titration of Vinegar by Sodium Hydroxide Vinegar Sample 1 Vinegar Sample 2 Vinegar Sample 3 Initial pH Reading pH = 3.211 pH = 3.102 pH = 3.105 Initial Buret Reading 2.89 mL 3.00 mL 1.61 mL Midpoint pH Reading pH = 4.895 pH = 4.687 Midpoint Buret Reading 12.92 mL 9.50 mL
Mejia - 7 -Final pH Reading pH = 8.238 pH = 8.531 pH = 8.934 Final Buret Reading 20.12 mL 20.31 mL 19.00 mL Volume of NaOH Consumed 17.24 mL17.31 mL17.38mLCalculated Molarity of Acetic Acid in the Vinegar Sample 0.86M0.87M0.86MVolume NaOH Consumed at Midpoint Reading 8.46 mL8.7MMoles of NaOH Consumed at Midpoint Reading [A–] 0.04398M0.042MMoles of Acetic Acid Remaining at Midpoint [HA] .01759M0.175MCalculated pKa 4.2894.314Average calculated molarity of acetic acid ______0.86M_____________________Average acetic acid concentration expressed in percent by mass ____17.2mL_______Average value of pKa of acetic acid based on provided experimental data ___4.3_________ Percent error for pKa of acetic acid ___7.9%________ ReferencesDetermination of Acetic Acid Concentration in Vinegar Using Titration. 2015. Carolina Biological Supply Company: Carolina Distance Learning Investigation Manual. Accessed 3/9/2020