Determination of An Unknown Amino Acid From Titration
Abstract
Experiment 11 used a titration curve to determine the identity of an
unknown amino acid. The initial pH of the solution was 1.96, and the pKa's
found experimentally were 2.0, 4.0, and 9.85. The accepted pKa values were
found to be 2.10, 4.07, and 9.47. The molecular weight was calculated to be
176.3 while the accepted value was found to be 183.5. The identity of the
unknown amino acid was established to be glutamic acid, hydrochloride.
Introduction
Amino acids are simple monomers which are strung together to form polymers
(also called proteins). These monomers are characterized by the general
structure shown in figure 1.
Fig. 1
Although the general structure of all amino acids follows figure 1, the presence
of a zwitterion is made possible due to the basic properties of the NH2 group
and the acidic properties of the COOH group. The amine group (NH2) is Lewis
base because it has a lone electron......
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