作者zinga (zinga)
看板Chemistry
标题生化问题
时间Mon Nov 13 21:35:08 2006
(1)
(A)Pyruvate pK1=2.86
(B)Propinoic acid pK1=4.86
(C)beta-hydroxybutyric acid pK1=4.70
(D)Lactic acid pK1=3.86
(E)Glutamate pK1=2.19
Which weak acid will be 91% neutralized at pH=4.86?
这题我用删去法删掉A B E 但是C D 又要怎麽判断呢??
题目问91% neutralized at pH=4.86是指pI值吧 没错吧??--->答案是D
(2)
What is the approximate charge diffrence between glutamate and
alpha-ketoglutarate at pH 9.5??--------->答案是 1/2
(3) A compound is known to have a free amino group with a pKa of 8.8
and one other ionizable group with a pKa between 5 and 7.
To 100 mL of a 0.2 M solution of this compound at pH 8.2 was added
40mL of a solution of 0.2 M HCl .
The pH changed to 6.2 The pKa of the second ionizble group is
(A)5.4
(B)5.6
(C)6.0
(D)6.2
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