試題詳解

21. Lysine H₃N⁺(CH₂)₄CH(NH₂)COO^-(denoted by HR) is an essential amino acid, and its hydrochloride salt ([H₃R]Cl₂) exists in aqueous solution in the following equilibrium: When an NaOH solution is added to a certain concentration of [H₃R]Cl₂ solution, the distribution cocfficients δ(x) of H₃R²⁺, H₂R⁺,  HR, and R^- vary with pH as shown on the right. Given that , which of the following statements is correct?

(A)
(B) At M, [CI^-] + [OH^-] +[R^-] =2[H₂R⁺] +[Na⁺] +H⁺]
(C) [H2R⁺], [HR], and [R^-] cannot be in the solution at the same time. 
(D)

(E) At P,[CI^-]>[Na⁺]>[OH^-] >[H⁺]