Experiment 20 - Lab#4 Experiment 20 pH Titration Phosphoric Acid in Cola Drinks Zach Hoffman Lab#4 Rachel Ojagbeghru Jennifer Morris Emilea Reiner I did

Experiment 20 - Lab#4 Experiment 20 pH Titration Phosphoric...

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Lab #4 Experiment 20: pH Titration: Phosphoric Acid in Cola Drinks Zach Hoffman Lab #4 Rachel Ojagbeghru, Jennifer Morris, Emilea Reiner September 30, 2014 I did not copy this work from any other students; current students or old lab reports.
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Lab #4 II. Data and Results Table 1 Sampl e Mass of KHP Volume of 0.01 M NaOH (mL) [NaOH] (M.) A 0.064 g. 39.1 0.008 B 0.064 g. 37.5 0.0084 Table 2 Volume of cola titrated (mL.) Initial pH 20 2.49 Table 3 volum e pH ΔpH Δvol (mL) ΔpH/ Δvol (V/mL) Aver. Vol. 0 2.49 0.95 2.53 0.0 4 0.95 0.042 0.475 2 2.61 0.0 8 1.05 0.076 1.475 3 2.7 0.0 9 1 0.090 2.5 3.97 2.77 0.0 7 0.97 0.072 3.485 5 2.87 0.1 1.03 0.097 4.485 6 2.97 0.1 1 0.100 5.5 7 3.11 0.1 4 1 0.140 6.5 8.1 3.29 0.1 8 1.1 0.164 7.55 8.6 3.4 0.1 1 0.5 0.220 8.35 9 3.49 0.0 9 0.4 0.225 8.8 9.7 3.68 0.1 9 0.7 0.271 9.35 10.2 3.87 0.1 9 0.5 0.380 9.95 10.6 4.09 0.2 2 0.4 0.550 10.4 11.1 4.45 0.3 0.5 0.720 10.85
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Lab #4 6 11.6 4.86 0.4 1 0.5 0.820 11.35 12 5.48 0.6 2 0.4 1.550 11.8 12.5 5.85 0.3 7 0.5 0.740 12.25 13.2 6.2 0.3 5 0.7 0.500 12.85 13.5 6.34 0.1 4 0.3 0.467 13.35 14.5 6.62 0.2 8 1 0.280 14 15.5 6.8 0.1 8 1 0.180 15 16.5 6.98 0.1 8 1 0.180 16 17.5 7.12 0.1 4 1 0.140 17 18.5 7.27 0.1 5 1 0.150 18 19.5 7.43 0.1 6 1 0.160 19 20.5 7.6 0.1 7 1 0.170 20 21.5 7.79 0.1 9 1 0.190 21 22 7.92 0.1 3 0.5 0.260 21.75 22.5 8.05 0.1 3 0.5 0.260 22.25 23 8.21 0.1 6 0.5 0.320 22.75 23.5 8.41 0.2 0.5 0.400 23.25 24 8.61 0.2 0.5 0.400 23.75 24.5 8.85 0.2 4 0.5 0.480 24.25 25 9.05 0.2 0.5 0.400 24.75 25.5 9.19 0.1 4 0.5 0.280 25.25 26 9.33 0.1 4 0.5 0.280 25.75 26.5 9.44 0.1 1 0.5 0.220 26.25 27 9.54 0.1 0.5 0.200 26.75 27.5 9.63 0.0 9 0.5 0.180 27.25
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Lab #4 28.5 9.78 0.1 5 1 0.150 28 29.5 9.87 0.0 9 1 0.090 29 30.5 9.97 0.1 1 0.100 30 31.5 10.0 5 0.0 8 1 0.080 31 0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233 0 1 2 3 4 5 6 7 8 9 10 11 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 1.600 1.800 Plot 1 Data First Derivative Volume (mL) pH ΔpH/ Δvol (V/mL) Table 4 Graphically Mathematically Actual pKa Actual Ka Vol. at equiv. point pKa determined Ka determined Ka Initial Conc. Of Ka1 11.8 2.97 0.00107 0.00656 0.00484 2.148 0.0071 Ka2 24.25 7.2 6.3x10 -8 N/A N/A 7.198 6.34x10 -8 b. Sample calculations i. Standardized molarity of “0.01 M” NaOH solution, trial 2 Equivalence Point Volume pH=pKa
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Lab #4 0.064 g( 1 mol 204.2 )=3.134x10 -4 mol/(0.0375 L)= 0.0084 Molar ii. Initial concentration of phosphoric acid in cola sample 0.0082(0.0118 L.)=(0.02)C 2 C 2 =0.00484 Molar iii. Ka1 calculated non-graphically, from initial pH and [H3PO4] Ka 1 = ( 0.00324 )( 0.00324 ) 0.00484 0.00324 = 0.00656 iv. Percent dissociation of H3PO4 in cola % dissociation= ( 0.00324 0.00484 )100 = 66.9% III. Discussion a. Objectives
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