作者jg065 (相信"相信的力量")
看板Chemistry
标题Re: 请问普化酸硷盐问题
时间Fri Mar 8 09:54:04 2013
※ 引述《runnial (呵呵)》之铭言：
: Pyridine, C5H5N, is a weak base and reacts with HCL as follows:
: C5H5N + HCL --> C5H5NH+ + Cl-
这个式子只是要告诉你C5H5NH+如何形成
形成後在水溶液中主要的离子就是C5H5NH+, Cl-
其中Cl-不水解
所以只要考虑C5H5NH+的水解就好
: What is the PH of a 0.015 M solution of the pyridinium ion(C5H5NH+)?
: The Kb for pyridine is 1.6*10^-9
: 可以告诉我如何解题吗?谢谢
C5H5NH+水解：
C5H5NH+ + H2O → C5H5N + H3O+
└───────┘
共轭酸硷对：Ka = Kw/Kb
[H+]*[A-] Kw
由 Ka = ────── = ──
[HA] Kb
[H+]^2 10^(-14)
=> ──── = ───────
0.015 1.6 * 10^(-9)
=> [H+] = 3.06 * 10^(-4)
=> pH = -log[H+] = 3.51 (离7很远，所以不用考虑水的自解离)
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