Milena Asatryan 605204517 Lab 2H Assignment Analysis of an Unknown Amino Acid I Statement of Purpose In the following experiment we are expected to use an acid base titration in order to examine an amino acid Based on the titration data we will find the pKa values including isoelectric pH value and the molarity of the amino acid With the three point method with buffers of pH 4 7 and 10 we will calibrate the pH meter After we shall begin the titration process of the amino acid by rinsing the buret with NaOH we will then set and initial volume of the NaOH prior to doing the titration simply by filling up the buret with the solution between a 0 00 to 1 00 mL marking Using a pipet we are expected to Fill a 125 mL beaker with a 10 00 mL aliquot of the amino acid Then make sure that the electrode tip is covered by adding 20mL of distilled water We are expected to record the pH of original amino acid solution and the pH of the final amino acid solution Titrate the amino acid solution with the standardized NaOH solution every 0 2 0 3 pH units taking pH and volume data Continue titrating until the pH reading falls between 12 and 13 Repeat the experiemnt one more time to ensure accuracy II Data Table Set Up for Titration Graph Titration of Unknown Amino Acid with NaOH Titration of Unknown Amino Acid with NaOH Trial 1 NaOH Volume mL 0 00 2 81 3 90 4 95 5 90 6 70 pH 2 04 2 39 2 63 2 91 3 25 3 66 Trial 2 NaOH Volume mL 0 00 2 92 4 17 5 02 5 97 6 57 pH 2 08 2 47 2 76 3 01 3 29 3 55 7 20 7 33 7 39 8 00 8 18 8 34 8 70 8 90 9 67 10 54 11 30 12 17 13 77 14 20 14 60 14 92 15 36 16 67 18 84 22 62 4 39 7 10 7 97 8 58 8 72 8 81 8 91 9 01 9 15 9 29 9 49 9 69 10 11 10 34 10 59 10 88 11 24 11 97 12 36 12 67 6 64 6 92 7 13 7 32 7 57 7 72 7 87 8 12 8 47 8 95 9 72 10 82 12 02 13 04 13 57 13 94 14 31 14 64 15 25 16 05 16 71 17 38 19 92 3 63 3 88 4 37 7 08 8 19 8 35 8 51 8 66 8 85 9 03 9 22 9 40 9 61 9 80 10 02 10 20 10 41 10 62 11 01 11 59 11 95 12 31 12 72 III Plotting Titration Graph 22 72 12 89 IV Data Analysis Unknown Acid Concentration Question 1 Trial 1 Equivalence point 1 6 17 Volume 7 30 mL Equivalence point 2 11 15 Volume 15 44 mL Trial 2 Equivalence point 1 6 28 Volume 7 35 mL Equivalence point 2 11 45 Volume 16 01 mL Question 2 NaOH M 0 2153 M 10 mL volumetric pipet Macidic protons x Vunknown acid MNaOH x VNaOH Trial 1 M1acid x 10 00 mL 0 2153M x7 30 mL M1acid 0 157M Trial 2 M2acid x 10 00 mL 0 2153Mx 7 35mL M2acid 0 158M Question 3 a The Average Macid M1acid M2acid 2 0 1577 0 158M b HA OH HA H2O i ii iii I 0 158M 0 2153M C E 0 158M 0 158M 0 158M 0 0573M 158M MHA 158M Question 4 Trial 1 pKa1 pH at Volume of 3 65mL PKa1 pH 2 54 Pka2 pH at volume of 7 72mL Pka2 pH 8 12 Trial 2 pka1 pH at volume of 3 68 mL Pka1 pH 2 65 Pka2 pH at volume of 8 00 mL Pka2 pH 8 57 Question 5 The isoelectric point pH IpH Trial 1 IpH pka1 pka2 2 2 54 8 12 2 5 33 Trial2 IpH pka1 pka2 2 2 65 8 57 2 5 61 Question 7 Trial 1 IpH is 6 18 Trial2 IpH is 6 28 Avg 6 18 6 28 2 6 23 Question 6 The average IpH for the amino acid based on the results from Q5 for the 2 trials Avg IpH 5 33 5 61 2 5 47 Question 8 Yes there is a significant difference more than 5 between the average IpH calculated from question 6 The significant percent difference is calculated by first subtracting 6 24 and 5 47 then dividing by 6 24 times 100 which equals to 12 2 So 12 2 is greater than 5
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