Buffer Analysis Lab

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The purpose of this lab is to understand the concepts of pH and buffers and how to make a buffer in the laboratory. Also, how to perform the titration process and identify the values of pKa, equivalence point, and the unknown buffer based on the titration process.
Data Analysis
C. The buffer we prepared in the lab had an actual pH of 7.30, while the theoretical pH of the buffer was 7.25. So, we had a percent error of 0.68%. The most possible reason for the error in the percent error could be because of the experimental procedure. Probably, the beaker was contaminated with some other chemicals and prior to the experiment the beakers were not cleaned properly. The other possibility can be that the right number of chemicals were not mixed while …show more content…

Water relatively has no buffering capacity, so when we added a drop of HCl in the water the pH of water dropped from 7.97 to 6.66. This indicates that water has a weak buffering capacity. While when we added a drop of HCl in our buffer solution, the pH went from 7.30 to 7.28. It did resisted pH change well. There was a very small change in the pH. Theoretically, the pH should have dropped a few units but again this could be the experimental errors occurring during the …show more content…

Titration of Buffer of Unknown #2

pH= pKa= 7.1
Equivalence point= 11.9
H. Our unknown #1 came out to be Imidazole. We figured out the unknown by plotting the titration graph for the pH of the buffer and the volumes of HCl added to it. By the titration curve we determined the pKa and its equivalence point. We calculated the pKa of the unknown by analyzing the graph and finding out the inflection point. The inflection point was 7.1 for 7.2 mL of HCl. The pKa was 7.1 which is closest to the value of imidazole. Our value is a bit higher which could be because of the experimental errors.
In addition to that, the equivalence point was found at pH of 11.9 at 3.86 mL of HCl titrated. The formula of imidazole is C3H4N2, so the molecular weight calculated to be 67.22 g/mol. The experimental errors could be the equipment’s being contaminated or during the titration process. We had error while dispensing the volume of HCl. Me and my partner dispensed 0.3 mL instead of 0.2 at one point. This might have affected the results. There could also be possibly an error in the weighing machine while measuring 800 g of the unknown

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