文档介绍：Chapter 4
Complexometric Titration
§§ Introduction
§ Equilibrium
§ Fundamental Principles of
Complexometric Titration
§ Selective Titration of Mixed ions
§ Modes and Application
VOCABULARY
Complexes 络合物 Chelates 螯合物
Ethylenediamine tetraacetic acid EDTA
Complexometric titration 络合滴定
Formation Constant 形成常数
Stability Constant 稳定常数
Instability Constant 不稳定常数
Accumulated Stability Constant 累积稳定常数
Conditional Stability Constant 条件稳定常数
Side Reaction 副反应
Metallochromic Indicator 金属指示剂
Eriochrome Black T 铬黑T Xylenol orange 二甲酚橙
Masking 掩蔽 Demasking 解蔽
§4-1 Introduction chelate
乙二胺- Cu 2+ 三乙撑四胺- Cu 2+
H H
H 2 H 2 2 2
N N N N
H C C H
H 2 C C H 2 2 2
C u C u
H 2C C H 2
H 2 C C H 2
N N N H N H
H 2 H 2
H 2C C H 2
lg K1=, lg K2=
lg K=
lg K总总总=
ethylene diamine tetra acetic acid
EDTA
H
HOOCH C + -
2 CH2COO
N CH2 CH2 N
-OOCH C + CH COOH
2 H 2
species solubility (22 ºC)
H4Y g / L
Na 2H2Y 111 g / L, mol /L
H
HOOCH C + -
2 CH2COO
N CH2 CH2 N
-OOCH C +
2 H CH2COOH

pKa1 = pKa2 = pKa3 =
-
H Y2+ H Y+ H4Y 4- H Y
6 2+ 5 2- 3- Y 3
H6Y H2Y HY
分
+
布 H5Y
p分K = pK = pK =
a4 2- a5 a6
数 H2Y HY 3- Y4-
分布系数-
H3Y

H4Y

0 2 4 6 8 10 12 14
EDTA 各种型体分布图 pH
H
HOOCH C + -
2 CH2COO
N CH2 CH2 N
-OOCH C + CH COOH
2 H 2
2N 4COO -
.. O ..
N C O
Ca-EDTA chelate
O
C
H2C H2
O C
CH2
N
H2C N
Ca CH2
C O
O O C
O CH2 O
C
O
Formation Constant
lg K lg K lg K lg K
Na + Mg 2+ Fe 2+ Hg 2+
Ag + Ca 2+ La 3+ Th 4+
Al 3+ Fe 3+
Zn 2+ Bi 3+
Cd 2+ ZrO 2+
Pb 2+
Cu 2+
§ Equilibrium
Stability Constant (K, βββ)
M + Y = MY
[MY] 1
K(MY)= K不稳=
[M][Y] K