i*******D
发帖数: 993 | 1 tris, boric acid, edta 配置出的tbe buffer。已知各个溶质的量。还有各个 pka,
pkb。该怎么求溶液中各种离子的浓度呢？就是求他们的分布系数对吧？那么是不是就
列几个质子平衡方程。貌似这个ph值我也不知道。
有一个文献 ionic effects on the equilibrium dynamics of dna confined in
nanoslits 里面测了不同浓度下这个buffer的离子强度。我的问题是，上述方法能算出
来吗？根据pka pkb那些算出的值跟实际相符得好吗？ | t******t
发帖数: 3045 | 2 大多数都可以近似解
比如NH4HCO3溶液 NH4＋和HCO3－占绝大部分， NH3和CO32-H2CO3很少 | t******t
发帖数: 3045 | 3 有pH就更容易了
Ka=[H+][A-]/[HA]
[A-]/[HA]=Ka/[H+] | v*****e
发帖数: 134 | 4 This is actually not easy as it might sound.
Assuming dilute solutions. With all pka, pkb known, it is mathematically
possible to solve all equations together. But in reality, these equations
are often of high degree and with multiple variables(多元高次方程). A
practical way to solve it is to use iterations (牛顿迭代法）.
An even more practical solution is to measure the pH and calculate every ion
conc accordingly, as 楼上 said. |
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