20 mL of 0.05 M solution of the conjugate acid of $α$ -amino acid methionine $(H_{2} A^{+})$ is taken. The $pK_{a}$ of (-COOH) group in methionine is 2.8 and $pK_{b}$ of basic group is 4.8.

Question

20 mL of 0.05 M solution of the conjugate acid of α -amino acid methionine ( H 2 ​ A + ) is taken. The pK a ​ of (-COOH) group in methionine is 2.8 and pK b ​ of basic group is 4.8.

TestHub · Accepted Answer

pH of original solution = 2 1 ​ ( pK a ​ + lo g C ) = 2 1 ​ ( 2.8 + lo g ( 0.05 )) = 2.05 Millimoles of amino acid=20×0.05=1 Millimoles of NaOH added in ' B ' option = 0.5 , so it will be acidic buffer. Millimoles of NaOH added in 'C' option=1, so amino acid exists as zwitter ion.

Chemistry - Ionic Equilibrium Question with Solution | TestHub

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