試題詳解

76. Alanine, H₂NCH(CH₃)CO₂H, has K_a = 4.5 × 10^–3 and K_b = 7.4 × 10^–5 . Which species has the highest concentration in water (pH=7.0)?
(A) H₂NCH(CH₃)CO₂H
(B) ⁺H₃NCH(CH₃)CO₂H
(C) H₂NCH(CH₃)CO₂^–
(D) H₂NCH(CH₃)CO₂H₂⁺
(E) ⁺H₃NCH(CH₃)CO₂^–