試題詳解

76. Alanine, H2NCH(CH₃)CO₂H, has Ka = 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 ^–