[化學] 一題酸鹼的考古題
原題目如下(去年台聯A5第二題):
A 100.0 mL sample of the triprotic weak acid H3A(0.200M) is titrated with
0.200M NaOH. Besides water and sodiunm ions, what are the major species
after 180.0 mL of 0.200 M NaOH is added in the titration?
(A)H2A-
(B)HA2-
(C)HA2-,A3-
(D)H2A-,HA2-
(E)A3-
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我的想法是:
此弱酸過量,鹼為限量試劑,所以此三質子弱酸會剩下 8 (mmol)
再來由於是弱酸,並非為完全解離,列出平衡系
H3A = H2A- + H+
H2A- = HA2- + H+
HA2- = A3- + H+
...但題目未給Ka1,Ka2,Ka3 我有點疑惑...是不是我思路錯誤??
望各位前輩指點迷津,謝謝!!
關於符號及數字方面很抱歉,化學式數字的下標及反應式的箭頭我不太會用...
再次謝謝各位...
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