100M solution of 0.1M glycine at pH 1.72 was titrated with 2M of sodium hydroxide solution.what is predominant species point of this amino acid?
To determine the predominant species point of the amino acid glycine at a given pH, we need to consider its acidic and basic properties. Glycine is a zwitterionic amino acid, meaning it has both an acidic carboxyl group (COOH) and a basic amino group (NH2).
At low pH values (acidic conditions), the carboxyl group will be protonated (COOH) and thus positively charged, while the amino group will be protonated (NH3+) and also positively charged. So both functional groups will have positive charges, resulting in the zwitterionic form of glycine, known as glycine zwitterion.
As the pH increases, the concentration of H+ ions decreases. At a certain pH, called the isoelectric point (pI), the net charge of the zwitterionic glycine becomes zero. At this point, the predominant species of glycine will be the neutral form, known as the zwitterionic glycine (not zwitterion), with no net charge.
To find the approximate pI of glycine, we look at the pKa values of its acidic and basic functional groups. The pKa value is a measure of the acidity or basicity of a compound. The pKa values for glycine are approximately 2.34 for the carboxyl group (pKa1) and 9.6 for the amino group (pKa2).
Given that the pH of the solution is 1.72, which is lower than the pKa1 value, the carboxyl group will be mostly protonated (COOH+). Since the solution is acidic and glycine has both functional groups positively charged, the predominant species point of glycine will be the zwitterionic form (glycine zwitterion).
It's important to note that without further information about the concentration of the glycine zwitterion in the titration solution, we cannot fully determine the exact predominant species at pH 1.72. However, based on the information provided, we can infer that the zwitterionic form of glycine (glycine zwitterion) is the predominant species.