The purpose of this experiment is to essentially repeat what we did in the previous lab which was to determine the Ka value using the pH titration curve that we derive We are going to monitor the changes in pH that occur during the titration of a weak polyprotic acid with a strong base At the equivalence point one should expect to see a dramatic change in pH as the solution goes from acidic to strongly basic In this lab we are working toward determining the Ka s for Coca Cola and Sprite and identify the type of acid using pH Catherine Callahan Chem 112 Lab 99LL Introduction Data Coca Cola Coca Cola pH NaOh added mL 2 7 2 9 3 1 3 3 3 5 3 7 3 9 4 1 4 3 4 5 4 7 4 9 5 1 5 3 5 5 5 7 5 9 6 1 6 3 6 5 6 7 6 9 0 0 8 1 05 1 4 1 55 1 85 2 2 3 2 4 2 6 2 65 2 95 3 2 3 8 4 4 2 4 5 4 75 5 5 4 5 6 6 1 7 1 7 3 7 5 7 7 7 9 8 1 8 3 8 5 8 7 8 9 9 1 9 3 9 5 9 7 9 9 10 1 10 3 10 5 10 7 10 9 11 1 11 3 6 2 6 4 6 6 6 8 6 9 7 7 15 7 25 7 5 7 6 7 7 7 8 8 2 8 5 8 6 9 6 11 9 12 7 13 5 19 5 25 8 36 9 Sprite Sprite pH NaOH added mL 3 5 3 7 3 9 4 1 4 3 4 5 4 7 4 9 5 1 5 3 5 5 5 7 5 9 6 1 6 3 6 5 6 7 6 9 0 0 7 1 4 1 8 2 4 3 3 8 4 4 4 8 5 3 5 8 6 2 6 8 7 1 7 4 7 6 7 85 7 9 7 1 7 3 7 5 7 7 7 9 8 1 8 3 8 5 8 7 8 9 9 1 9 3 9 5 9 7 9 9 10 1 10 3 10 5 8 8 1 8 2 8 2 8 3 8 35 8 4 8 55 8 9 9 5 10 2 11 4 11 9 12 12 7 13 3 13 8 14 5 Calculations Coca Cola Equivalence points V1 10 1mL NaOh V2 2 10 1 20 2mL NaOH V3 3 10 1 30 3 ml NaOH At midpoints Vmid 1 0 5 10 1 5 05 Vmid 2 0 5 10 1 20 2 15 15 Vmid 3 0 5 20 2 30 3 25 25 Mid 1 pH 5 pka 5 Ka 10 5 1x10 5 Mid 2 pH 15 15 pka 15 15 Ka 10 15 15 7 0794578E 16 Sprite Three Equivalence points 7 9 pH 8 3 mL V1 8 3 mL V2 16 6mL V3 24 9mL Midpoints Vmid1 0 5 8 3 4 15 mL Vmid 2 0 5 8 3 16 6 12 45 mL V mid 3 0 5 16 6 24 9 20 75 mL Mid 1 pH 4 8 pka 4 8 Ka 10 4 8 1 58E 5 Mid 2 pH 9 8 pka 9 8 Ka 10 9 8 1 5848932E 10
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