Question

Why does acetic acid have only one pKa value and our amino acids have two?

Answer 1

Acetic acid (
`CH_(3)COOH`) can release only one single H+ ion .

Therefore we can say that acetic acid has only one pKa value.

Amino acids have one -COOH( carboxylic group) group and one -NH​​​​​​2​ (amino group) group which can both release one single H+ ion.

Step-by-step explanation:

Acetic acid (
`CH_(3)COOH`) can release only one single H+ ion .

Therefore we can say that acetic acid has only one pKa value.

Amino acids have one -COOH( carboxylic group) group and one -NH​​​​​​2​ (amino group) group which can both release one single H+ ion.

In amino acids -
`NH_(2)` group becomes
`-NH_(3)^(+)` in the presence of acids.

in the presence of bases
`-COOH` becomes
`-COO^(-)`

Therefore two pKa values can be observed amino acids.