What is the pH at which form B predominates An ionization st

What is the pH at which form B predominates?

An ionization step for the amino acid serine is written below: What is the pH at which form B predominates? at pH 8.0 at pH 3.0 pH 8.0

Solution

The form B loses 1 proton.

The PK₁ = 3.0 and PK₂ = 8.0

pH = PK₁ + PK₂ / 2 = 11/2 = 5.5

The form B predominates at pH= 5.5. Option 4 is correct.