作者doppi (take me away)
看板TransBioChem
標題[化學] About titration question
時間Sat Jun 30 01:54:31 2012
The titration of 100.0 mL of a 0.100 M solution of weak acid H3A with
0.200 M NaOH is carried out. What are the major species (except water) at
each of the following specified points in the titration?
A) HA2-, after 100.0 mL NaOH is added
B) H2A- and HA2-, after 40.0 mL NaOH is added
C) HA2- and A3-, after 120.0 mL NaOH is added
D) HA2-, after 50.0 mL NaOH is added
E) H2A- and HA2-, after 85.0 mL NaOH is added
F) none of the above
我的問題是這樣子
H3A -> H2A- -> HA2- > A3-
0 50 ? ?
就是我不知怎麼算HA2-是100 A3-是150
希望有神手可以替我解答 感恩
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1F：→ o810418:沒有Ka? 06/30 14:47
2F：→ o810418:沒有Ka的話會不太好判斷 到滴定終點大約是HA2- 之前是H2A 06/30 14:48
3F：→ o810418:超過很多才會有A3- 因為Ka非常小 要強鹼環境才解離 06/30 14:48
4F：→ o810418:沒Ka的話就拿磷酸試試看QQ 應該差不多像那樣 06/30 14:49