試題詳解

10. Consider the titration of 50.0 mL of 0.100 M NaH₂PO₄(aq) with 0.100 M NaOH(aq). For H₃ PO₄, = 7.5 x . Three pH values during the titration are listed as follows.
(1) Before the addition of NaOH(aq), the pH is x.
(2) After the addition of 25.0 mL NaOH(aq), the pH is y.
 (3) After the addition of 50.0 mL NaOH(aq), the pH is z.
Which of the following statements about x, y, and z is correct? (log2 = 0.301,10g3 = 0.477,log5=0.699)
(A)x＜4,y＞7
(B)x>4，z>10
(C)y＞7,z＜10
(D)y＞8,z＞9