5

Complexometric Titrations

5-1 5-2 5-2-1 5-2-2 5-3 5-4

5-1 N(CH2COOH)2

H4Y H6Y2+

EDTA ~ K p.96 Na2H2Y 2H2O 11.1g /100ml H2Y2- + Mn+ === MYn-4 + 2H+ H2Y + M === MY + 2H+

EDTA pH pH EDTA pH Mn+ K ~ K ~

5 - 2 lg KMY = lg KMY - lg M - lg Y lg KMY = lg KMYlg (M(L)+ M(L) ) lg( Y(H)+ Y(N) ) M(L)M(L)Y(H)Y(N)

lgM=pM-pMpM=pM+lgM

5 - 2 5- 2 - 1 0.01000mol/L EDTA 20.00ml 0.01000mol/L Mn+ lgKMY= 17.0lg Y = 5.0lg M= 4.0 lgK MY = lg KMY lg Y lg M = 17.0 5.0 4.0 = 8.0 1 2 3 41. 2. 3. 4.

1. pM = 2.00 pM = 6.0 Ep (-0.1%) pM = 5.0 pM = 9.0 Ep pM = 5.2 pM = 9.2 Ep (+0.1%) pM = 5.3 pM = 9.3pM = pM + lg M

2. cM MY K cM Ep Ep K cM Ep K Ep Ep cM K Ep

2. cMK MY lg cMK MY 6.0 TE 0.1% pM 0.2 lg cMK MY 6 0.3pM

2. cM cL M(L) K cN Y(N) K Y(H)Y(H)>> Y(N)K Y(H)

3. Ep [M]Ep= [Y]Ep ep [M]ep= [Y]ep EDTA M Ep a = [M]ep- [Y]ep Ep a = [Y]ep- [M]ep

M EDTA Ringbom

Ringbom

()

Ringbom 1. cK pM TE% p.110 1 2. cK pM(TE%) p.111 3 3. pM cK p.111 2 0.1% pMep ~ pMt ~ pMEplgcMK MY 6.0

4. lg cMK MY 6.0 TE 0.1% pM 0.2 cM=10 -2 mol/L lg K MY 8.0 lg K MY lg Y(H) 8.0 lg Y(H) lg K MY 8.0 pH ~ lg Y(H)pH ~ lg K MY lg Y(H) + 8.0______ pH M

pH 1~2 pH 5~6 ~ pH 10

Mn+ epEp

5 2 2 1. In + M MIn

+ H+ ||HIn

MIn ~ lgKMIn = lg KMIn - lg In(H) MIn

5 2 2 1. In + M MIn

+ H+ ||HIn

pMt = lgKMIn pMt = lgKMIn 1

MIn ~ lgKMIn = lg KMIn - lg In(H)

pMep = pMt = lgKMIn ||pMEp pMt pMEp pHpMt p.114

2. TEriochrome Black TEBT 1-(1--2-)-5--2--4- pKa=6.3 pKa= 11.6H2In- HIn2- In3-

Mg2+Zn2+Pb2+ Cd2+ Mn2+ M - EBTpH7 11

Xylenol OrangeXO 3,3-[N,N-()]-- pKa=6.3H7In+ H3In- H2In4- In5-

pH 5 6 Pb2+Zn2+Cd2+Hg2+ pH 1 2 Bi3+ M - XO pH 6.3

PAN1-(2-pyridylazo)-2-naphthol 1- ( 2- ) -2- pKa=1.9 pKa= 12.2 H2In+ HIn In-

Cu2+Zn2+Cd2+In3+ M - PAN pH2 12

Cu - PAN CuY + PAN + M CuPAN + MY Cu - PANpH MN pHCuYpMep pM M EDTA

M

CuY

Cu - PAN CuY + PAN + M CuPAN + MY EDTA

M

CuY1[MY] pMepKCuPAN pHpH[CuY]ep

3. pH Mn+ epEp

(1) EDTA+M lgKMY

(2) ~ pHpM ~ pH lgKMY ~ lgY(H) ~ pH3. pH pH TE% pMep= pMt ~ pHpMEP ~ pH

5-3 N(M) M, pM 0.2 TE 0.1% lg cK 6.0 TE 0.3% lg cK 5.0 TE 1% lg cK 4.0Y(H)>> Y(N)NK Y(H)

5-3-2 1. lg cK 5.0

N M lg cK 6.0 5.0 M N MN lg cK 6.0 5.0 (1) M N (2) lg cK 5.0 [N]

2.

KNLn > KNY KMLn < KMY pH pH pH(1) (2) Bi3+~ Fe3+ (3) Ca2+~ Mg2+ (4) HCN~

p.121 ~ 1. Fe3+Al3+Ti4+Sn4+ 2. F - NH4FNH4HF2 NaF Al3+Ti4+Sn4+ Fe3+CaF2 MgF2 Al ~ Zn3. Cu2+Zn2+Cd2+Co2+Ni2+Ag+Hg2+ Fe2+ HCN KCN ~ (1) PbCaMgMnRE (2) ZnCd (3) CuCoNiHg

5 - 4 1. pH56PbZn 2. (N) NY MY

3. (1) M + NY === ML + N 2 Ag+ + Ni(CN)42- = 2 Ag(CN)2- + Ni2+ (2) EDTA MY + L === ML + Y Al ~ ZnCuPbCdBi (3) M + In + NY === MY + NIn Cu-PAN EBTCa ~ MgYEDTAN

4. MY p.124 PO43- PO43- MgNH4PO4 Mg ( + ) Mg PO43- Mg