Attempt titrating an amino acid against a weak base and discover the number of dissociating (ionizable) functional groups in the amino acid.

To titrate an amino acid against a weak base and determine the number of dissociating (ionizable) functional groups, you would typically perform a titration experiment and analyze the titration curve. Here's a general outline of how you can do this:

1. Preparation: Prepare a solution of the amino acid at a known concentration. You'll need to know the pKa values of the functional groups in the amino acid you're titrating. These values can be found in literature or databases.

2. Titration Setup: Set up a titration apparatus with a burette containing the weak base solution (titrant) and a flask containing the amino acid solution. Use a suitable indicator that changes color within the pH range of the titration.

3. Titration Procedure: Slowly add the weak base solution (titrant) from the burette into the flask containing the amino acid solution while stirring continuously. Record the volume of titrant added at regular intervals or pH measurements using a pH meter.

4. Titration Curve: Plot the volume of titrant added (or pH) versus the pH of the solution. As you titrate, the pH of the solution will change. The titration curve will typically exhibit characteristic shapes depending on the number of ionizable functional groups present in the amino acid.

5. Interpretation: Analyze the titration curve to determine the equivalence points and the buffering regions. The number of dissociating functional groups can be inferred from the number of equivalence points observed on the titration curve.

   • One Equivalence Point: If there's only one equivalence point observed, it suggests that the amino acid has one dissociating functional group. This would be the case for amino acids like glycine, which has only one carboxyl group.

   • Two Equivalence Points: If two equivalence points are observed, it indicates that the amino acid has two dissociating functional groups. For example, amino acids with both amino and carboxyl groups, such as alanine or lysine, would exhibit two equivalence points.

6. Calculations: Use the volume of titrant added at each equivalence point to calculate the concentration of the weak base and determine the pKa values of the functional groups in the amino acid. These values can be compared to literature values for identification.

By following these steps and analyzing the titration curve, you can determine the number of dissociating functional groups present in the amino acid being titrated.