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Biomolecules — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryBiomolecules3 Marks
Question
The monoamino monocarboxylic acids have two $pK_a$ values.
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Answer

In aqueous solution, monoamino monocarboxylic acid behave like salt at isoelectric point. At a pH lower than isoelectric point (i.e., in acidic medium) it showsone pKa value which corresponds to structure $\text{R}-\text{CH}-\text{COOH}\\ \ \ \ \ \ \ \ \ \ \text{|}\\\ \ \ \ \ ^+\text{NH}_3$ and at a pH higher than isoelectric point (i.e., basic medium), it shows another $pK_a$ value which corresponds to structure $\text{R}-\text{CH}-\text{COO}^-\\ \ \ \ \ \ \ \ \ \ \text{|}\\\ \ \ \ \ \text{NH}_2$

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