Attempt titrating an amino acid against a weak base and discover the number of dissociating ( ionizable ) functional groups in the amino acid.
Explanation A titration is a technique where a solution with known concentration is used to determine the concentration of an unknown solution. The known concentration solution (called titrant) is added slowly from a burette to a known quantity of the unknown concentration solution (called analyte) until the reaction is complete. Indicator is used which change its colour and that indicate the endpoint of reaction. There are three types of amino acids- neutral, acidic and basic. When we titrate these three types of amino acids with weak base, it will give different number of dissociation ionisable functional groups. When we titrate a basic amino acid (for example arginine) against a weak base, it will give only one ionisable functional group. If we titrate a neutral amino acid (for example alanine) against a weak base, it will give only one ionisable functional group. If we titrate an acidic amino acid (for example aspartic acid) against a weak base, it will give two or more than two ionisable functional group. Opinion: Amino acid is generally considered as a weak acid. So when we are titrating an amino acid with weak base we can use an indicator with a range of pH 6-8. Phenolphthalein can be used as indicator for titration. At the endpoint of titration, the colour change into pink, which indicate that the reaction is completed. Final Answer Titration of amino acids with weak base dissociates one ionisable group in case of basic and neutral amino acids, and dissociates two or more ionisable group in case of acidic amino acids.
