CHEM2 lab 8

CHEM2 lab 8 - 7.30 by use of the Henderson Hasselbach...

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Bobby Bardin II 11/7/07 Chemistry experiment 8 Buffer Capacity Purpose: The purpose of this lab was to prepare a buffered solution and to observe how a buffered solution works by titrating the solution with both an acid and a base. The buffered capacity and the pKa were also found by use of graphic software to graph the pH in relation to volume. Procedure: Please refer to the hand out for Exp. # 8 Buffer Capacity Data and Observations: For the prelaboratory assignment: Case 1 was graph B, case 2 was graph D, case 3 was graph C, and Case 4 was graph A. Please refer to the graphs for part A. Unknown 5 was used during this lab. Results: Looking at the titration curves it is apparent that the original solution mixed with HCl was the buffered solution, and so unknown number 5 was a weak base. From looking at the graphs it can be determined that the pKa of the reaction is
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Unformatted text preview: 7.30 by use of the Henderson Hasselbach equation: pH = pKa + log [A- / AH] pKa = pH log [A- / AH] = 8 log[ .5 / .1 ] total buffer range 1 2 3 4 5 6 7 8 9 10-4-3-2-1 1 2 3 mmol acid added pH Series1 From the graph of the total range of the buffer solution it can be determined that the range was up to 2.4 mmol acid and 3 mmol base. Discussion: The goal of this experiment was accomplished because the pKa of a buffered solution was found to be 7.3 by and the buffered capacity of the solution was found to be that the buffered solution works for up to 2.4 mmol of acid and 3.0 mmol of base because the pH range remains steady and only changes +/- 1 within these boundaries. . By looking at the graphs is can be determined that unknown 5 was a weak base because it formed a buffered solution when mixed with a strong acid....
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CHEM2 lab 8 - 7.30 by use of the Henderson Hasselbach...

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