Which is the main species present in an aqueous solution of aspartic acid at pH = 14? A H CH$_2$COOH C H COOH B CH$_2$COOH COOH C H CH$_2$COOH COO$^-$ D H CH$_2$COO$^-$ NH$_2$ COO$^-$ - AQA - A-Level Chemistry - Question 29 - 2022 - Paper 3

At pH 14, aspartic acid exists primarily in its deprotonated form because the pH is significantly higher than the pKa values of the carboxylic acid groups in aspartic acid. Therefore, the amino acid will exist as an anion due to the loss of protons from the acidic side groups. Among the options provided, the correct structure is represented by option D, where aspartic acid is in its anionic form (CH$_2$COO$^-$) rather than its protonated forms.