Weak Acid Titration Discussion

Weak Acid Titration Discussion - closest acid of the 4...

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Weak Acid Titration Lab
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VII – Discussion: The identity of the weak acid, A1, which had a 4.25 pKa value, is Glutamic acid. That was found with the calculation of the [A-] and the [HA] values. With those values, and the values of the equivalence point, 0.01225 L, and the half equivalence point, 0.006125 L, I was able to match the identity of the unknown acid. The half equivalence point, 6.125 mL (in mL), is directly in between 5 mL and 7 mL. Between 5 mL and 7 mL, the pH levels are from 4.05 to 4.32, respectively. The pH level is equal to the pKa value. In between the two pH levels above, there are 4 acids that could be the unknown acid. But, because the molecular weight is 156.47 grams/mole, it matched the closest with Glutamic acid, which had a molecular weight of 147.13 grams/mole. The other
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Unformatted text preview: closest acid of the 4 total is Glutaric acid, with a molecular weight of 132.13 grams/mole. The Ka value obtained, 5.62 x 10-5 Ka value, was found by obtaining the pKa value. The pKa value obtained, 4.25 pKa value was set equal to the negative log of the Ka value, and that was how it was found. The accuracy of the Ka value is important because it requires an accurate pKa value. The Ka value found, 5.62 x 10-5 Ka value, directly matches the Glutamic acid, which in the lab notebook, is 5.6 x 10-5 Ka value. The molecular weight in the experiment of the A1 acid, is slightly off from the value of the Glutamic acid, 147.13 grams/mole. The value obtained is 156.47 grams/mole, which is somewhat accurate....
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This note was uploaded on 09/22/2008 for the course CHEM 104B taught by Professor Staff during the Spring '07 term at University of Arizona- Tucson.

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Weak Acid Titration Discussion - closest acid of the 4...

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