Titration: Identification of an Unknown Amino Acid Essay Example

align="justify">In the case of amino acids, the iterant will be both an acid and a base. The pH at which the net charge of an amino acid Is zero Is called the Sclerotic point, or the Pl.

The Pl could be determined by averaging the two peak values that flank the neutral species. At the Pl, the a-carboxylic group Is a negatively charged carboxylic Ion, the a-amino group Is a positively charged ammonium Ion, and the y-carboxylic group Is a neutral propionate acid (1). In this experiment, the Identity of an unknown amino acid was determined through acid-base titration.

The unknown amino acid could be glutamate, lysine, or histamine. The glycerin was also titrated for comparison (Fig.

2). Figure 2. The structural formulas of four amino acids at pH of 7. 0. Methods experiment was accomplished according to the procedure given by Professor. Results glycerin was titrated and dada was recorded.

The total solution of Noah added was 28. 0 ml; the total solution of HCI added was 22. 0 ml (Fig. 3).

Added was 40. 0 ml; the total solution of HCI added was 17. 0 ml (Fig. 4).

Figures 3 and 4 represent the exploratory titration and the accurate titration curves respectively.

Also, the dots on figures 3 and 4 show the amounts of base and acid added to the unknown solution and the pH which corresponds to that amount. Discussion and Conclusions titration of a weak acid with a strong base is an excellent way to observe the equilibrium reactions associated with a weak acid. The analysis of the titration curves provides a means of determining the dissociation constant of the acid.

Under ideal conditions the dissociation can be used to identify an unknown acid. The peak of the acid is equal to the pH at the midpoint of the titration curve.

To identify the unknown amino acid its peak was used as a comparison to the known value of lysine, histamine, and glutamate. The equivalence point of titration from the titration curve of the unknown amino acid was estimated. It was found that the equivalence point of the first, second, and third peak(s) are approximate at a pH of 2. 48, 4. 86, and 9. 84.

These values were been compared with lysine, histamine, and glutamate peak(s). It was determined that the peak(s) of the unknown amino acid were very close to the peak(s) of glutamate (2. 10, 4. 07, 9. 47). It was assumed that the known amino acid was glutamate.

There was an error that can be held accountable for the deviation from the accepted values. First, the pH meter never reported a definite value; very often the meter reported a floating number. Therefore, one has no way of knowing which reported pH was more correct. To avoid such a problem in a future, more careful handling with equipment is necessary during the titration process to minimize the occurrence of error. References(l) Identification of an Unknown Amino Acid. 12 September 2008.

(2) Equilibrium: Titration Curve of Amino Acid. 12 September 2008.