Appendix
Solubility Products
Bromide (Br –)
pKsp
CuBr
8.3
Ksp
5 × 10–9
AgBr
Hg2Br2
12.30
22.25
5.0 × 10–13
5.6 × 10–23
HgBr2(µ = 0.5 M)
PbBr2(µ = 4.0 M)
18.9
5.68
1.3 × 10–19
2.1 × 10–6
Carbonate (CO32–)
pKsp
MgCO3
7.46
3.5 × 10–8
CaCO3 (calcite)
CaCO3 (aragonite)
8.35
8.22
4.5 × 10–9
6.0 × 10–9
SrCO3
BaCO3
MnCO3
9.03
8.30
9.30
9.3 × 10–10
5.0 × 10–9
5.0 × 10–10
10.68
9.98
2.1 ×
1.0 × 10–10
6.87
11.09
1.3 ×
8.1 × 10–12
Hg2CO3
ZnCO3
16.05
10.00
8.9 ×
1.0 × 10–10
CdCO3
PbCO3
13.74
13.13
1.8 × 10–14
7.4 × 10–14
FeCO3
CoCO3
NiCO3
Ag2CO3
Ksp
10–11
10–7
10–17
Cyanide (CN–)
AgCN
Zn(CN)2 (µ = 3.0 M)
Hg2(CN)2
Cd2[Fe(CN)6]
Pb2[Fe(CN)6]
17.38
18.02
4.2 × 10–18
9.5 × 10–19
Fluoride (F–)
pKsp
8.18
10.41
6.6 × 10–9
3.9 × 10–11
SrF2
BaF2
8.54
5.76
2.9 × 10–9
1.7 × 10–6
PbF2
7.44
3.6 × 10–8
Hydroxide (OH–)
pKsp
Ksp
Mg(OH)2
Ca(OH)2
Ba(OH)2 8H2O
La(OH)3
11.15
5.19
3.6
20.7
7.1 × 10–12
6.5 × 10–6
3 × 10–4
2 × 10–21
12.8
15.1
14.9
15.2
1.6 × 10–13
8 × 10–16
1.3 × 10–15
6 × 10–16
19.32
38.8
4.8 × 10–20
1.6 × 10–39
44.5
3 × 10–45
15.42
29.4
3.8 × 10–16
4 × 10–30
15.52
14.35
3.0 × 10–16
4.5 × 10–15
⋅
1.9 × 10–7
AgCl
9.74
1.8 × 10–10
17.91
4.78
1.2 × 10–18
1.7 × 10–5
Cu(OH)2
Fe(OH)3
BaCrO4
CuCrO4
Ag2CrO4
9.67
5.44
11.92
2.1 ×
3.6 × 10–6
1.2 × 10–12
Hg2CrO4
8.70
2.0 × 10–9
10–10
Ksp
MgF2
CaF2
6.73
Ksp
Ksp
2.1 × 10–16
CuCl
pKsp
2.2 × 10–16
3 × 10–16
5 × 10–40
15.68
Mn(OH)2
Fe(OH)2
Co(OH)2
Ni(OH)2
Chromate (CrO42–)
pKsp
Ksp
Zn2[Fe(CN)6]
pKsp
Hg2Cl2
PbCl2
15.66
15.5
39.3
Ferrocyanide ([Fe(CN)64–])
Chloride (Cl–)
Ksp
pKsp
Co(OH)3 (T = 19 °C)
Ag2O (+H2O
Cu2O (+ H2O
2Ag+
t
t 2Cu
+
Zn(OH)2 (amorphous)
Cd(OH)2 (β)
2OH–)
+
+ 2OH–)
continued
Solubility Products—continued
Hydroxide (OH–)
pKsp
Ksp
25.44
3.6 × 10–26
Al(OH)3 (α)
26.2
15.1
33.5
6×
8 × 10–16
3 × 10–34
Iodate (IO3–)
pKsp
Ksp
6.15
8.81
7.1 ×
1.5 × 10–9
HgO (red) (+ H2O
2+
–
t Hg + 2OH )
SnO (+ H O t
+ 2OH )
PbO (yellow) (+ H O t Pb + 2OH )
2
Sn2+
2
–
2+
–
Ca(IO3)2
Ba(IO3)2
10–27
Sulfate (SO42–)
pKsp
CaSO4
SrSO4
BaSO4
4.62
6.50
9.96
2.4 × 10–5
3.2 × 10–7
1.1 × 10–10
Ag2SO4
Hg2SO4
4.83
6.13
1.5 × 10–5
7.4 × 10–7
PbSO4
7.79
1.6 × 10–8
Ksp
10–7
7.51
3.1 × 10–8
17.89
1.3 × 10–18
Sulfide (S2–)
pKsp
Ksp
Zn(IO3)2
Cd(IO3)2
5.41
7.64
3.9 ×
2.3 × 10–8
MnS (green)
13.5
3 × 10–14
18.1
8 × 10–19
12.61
2.5 × 10–13
FeS
Pb(IO3)2
Iodide (I–)
pKsp
AgI
Hg2I2
16.08
28.33
8.3 × 10–17
4.7 × 10–29
CoS (β)
NiS (γ)
CuS
25.6
26.6
36.1
3 × 10–26
3 × 10–27
8 × 10–37
HgI2 (µ = 0.5 M)
PbI2
27.95
8.10
1.1 × 10–28
7.9 × 10–9
Cu2S
Ag2S
ZnS (α)
48.5
50.1
24.7
3 × 10–49
8 × 10–51
2 × 10–25
Oxalate (C2O42–)
pKsp
Ksp
CdS
Hg2S (red)
27.0
53.3
1 × 10–27
5 × 10–54
CaC2O4 (µ = 0.1 M, T = 20 °C)
BaC2O4 (µ = 0.1 M, T = 20 °C)
7.9
6.0
1.3 × 10–8
1 × 10–6
PbS
27.5
3 × 10–28
SrC2O4 (µ = 0.1 M, T = 20 °C)
6.4
4 × 10–7
pKsp
Ksp
Thiocyanate (SCN–)
pKsp
CuSCN (µ = 5.0 M)
13.40
4.0 × 10–14
AgSCN
Hg2(SCN)2
11.97
19.52
1.1 × 10–12
3.0 × 10–20
Hg(SCN)2 (µ = 1.0 M)
19.56
2.8 × 10–20
AgIO3
Hg2(IO3)2
Phosphate (PO43–)
⋅
⋅
Fe3(PO4)2 8H2O
Zn3(PO4)2 4H2O
Ag3PO4
Pb3(PO4)2 (T = 38 °C)
36.0
35.3
17.55
43.53
10–6
Ksp
1 × 10–36
5 × 10–36
2.8 × 10–18
3.0 × 10–44
Ksp
Source: All values are from Martell, A. E.; Smith, R. M. Critical Stability Constants, Vol. 4. Plenum Press: New York, 1976. Unless otherwise stated, values
are for 25 °C and zero ionic strength.
Acid Dissociation Constants
Compound
Conjugate Acid
pKa
acetic acid
CH3COOH
4.757
1.75 × 10–5
adipic acid
HOOC(CH2)4COOH
4.42
5.42
3.8 × 10–5
3.8 × 10–6
alanine
COOH
2.348 (COOH)
4.49 × 10–3
9.867 (NH3)
1.36 × 10–10
4.601
2.51 × 10–5
Ka
CHCH3
NH3+
aminobenzene
NH3+
Compound
Conjugate Acid
pKa
4-aminobenzene sulfonic acid
–O S
3
2-aminobenzoic acid
Ka
3.232
5.86 × 10–4
2.08 (COOH)
4.96 (NH3)
8.3 × 10–3
1.1 × 10–5
4.78 (NH3); (T = 20 °C)
9.97 (OH); (T = 20 °C)
1.7 × 10–5
1.05 × 10–10
9.244
5.70 × 10–10
1.823 (COOH)
8.991 (NH3)
(12.48) (NH2)
1.50 × 10–2
1.02 × 10–9
3.3 × 10–13
NH3+
COOH
NH3+
2-aminophenol
OH
NH3+
ammonia
NH4+
arginine
COOH
NH2+
CHCH2CH2CH2NHC
NH2
NH3+
arsenic acid
H3AsO4
2.24
6.96
11.50
5.8 × 10–3
1.1 × 10–7
3.2 × 10–12
asparagine
COOH
2.14 (COOH); (µ = 0.1 M)
8.72 (NH3); (µ = 0.1 M)
7.2 × 10–3
1.9 × 10–9
1.990 (α-COOH)
3.900 (β-COOH)
10.002 (NH3)
1.02 × 10–2
1.26 × 10–4
9.95 × 10–11
4.202
6.28 × 10–5
9.35
4.5 × 10–10
9.236
(12.74); (T = 20 °C)
(13.80); (T = 20 °C)
6.352
10.329
9.40
12.8
5.81 × 10–10
1.82 × 10–13
1.58 × 10–14
4.45 × 10–7
4.69 × 10–11
4.0 × 10–10
1.6 × 10–13
CHCH2CNH2
NH3+ O
aspartic acid
COOH
CHCH2COOH
NH3+
benzoic acid
COOH
benzylamine
CH2NH3+
boric acid
H3BO3
carbonic acid
H2CO3
catechol
OH
OH
continued
Acid Dissociation Constants—continued
Compound
Conjugate Acid
chloroacetic acid
chromic acid
ClCH2COOH
H2CrO4
citric acid
pKa
COOH
HOOCH2C
C
CH2COOH
Ka
2.865
–0.2; (T = 20 °C)
6.51
1.36 × 10–3
1.6
3.1 × 10–7
3.128 (COOH)
4.761 (COOH)
6.396 (COOH)
7.45 × 10–4
1.73 × 10–5
4.02 × 10–7
4.16; (µ = 0.1 M)
6.9 × 10–5
(1.71) (COOH)
8.36 (SH)
10.77 (NH3)
1.9 × 10–2
4.4 × 10–9
1.7 × 10–11
OH
cupferron
NO
N
OH
cysteine
COOH
CHCH2SH
NH3+
dichloroacetic acid
diethylamine
dimethylamine
Cl2CHCOOH
(CH3CH2)2NH2+
(CH3)2NH2+
1.30
10.933
10.774
5.0 × 10–2
1.17 × 10–11
1.68 × 10–11
dimethylgloxime
HON
10.66
12.0
2.2 × 10–11
1 × 10–12
10.636
6.848
9.928
2.31 × 10–11
1.42 × 10–7
1.18 × 10–10
0.0 (COOH); (µ = 1.0 M)
1.5 (COOH); (µ = 0.1 M)
2.0 (COOH); (µ = 0.1 M)
2.68 (COOH); (µ = 0.1 M)
6.11 (NH); (µ = 0.1 M)
10.17 (NH); (µ = 0.1 M)
1.0
3.2 × 10–2
1.0 × 10–2
2.1 × 10–3
7.8 × 10–7
6.8 × 10–11
3.745
1.80 × 10–4
3.053
4.494
8.85 × 10–4
3.21 × 10–5
2.23 (α-COOH)
4.42 (λ-COOH)
9.95 (NH3)
5.9 × 10–3
3.8 × 10–5
1.12 × 10–10
NOH
CH3
H3C
ethylamine
ethylenediamine
CH3CH2NH3+
+H NCH CH NH +
3
2
2
3
ethylenediaminetetraacetic acid (EDTA)
HOOCH2C
CH2COOH
+
HNCH2CH2NH+
HOOCH2C
formic acid
CH2COOH
HCOOH
fumaric acid
COOH
HOOC
glutamic acid
COOH
CHCH2CH2COOH
NH3+
Compound
Conjugate Acid
glutamine
COOH
pKa
O
Ka
2.17 (COOH); (µ = 0.1 M)
9.01 (NH3); (µ = 0.1 M)
6.8 × 10–3
9.8 × 10–10
2.350 (COOH)
9.778 (NH3)
3.831 (COOH)
4.47 × 10–3
1.67 × 10–10
1.48 × 10–4
1.7 (COOH); (µ = 0.1 M)
6.02 (NH); (µ = 0.1 M)
9.08 (NH3); (µ = 0.1 M)
2 × 10–2
9.5 × 10–7
8.3 × 10–10
9.21
3.17
11.65
7.02
13.9
0.9
6.2 × 10–10
6.8 × 10–4
2.2 × 10–12
9.5 × 10–8
1.3 × 10–14
1.3 × 10–1
4.91 (NH)
9.81 (OH)
1.23 × 10–5
1.55 × 10–10
CHCH2CH2CNH2
NH3+
glycine
+H NCH COOH
3
2
glycolic acid
HOCH2COOH
histidine
H
N
COOH
CHCH2
N
H+
NH3+
hydrogen cyanide
hydrogen fluoride
hydrogen peroxide
hydrogen sulfide
HCN
HF
H2O2
H2S
hydrogen thiocyanate
HSCN
8-hydroxyquinoline
N
H+
OH
hydroxylamine
hypobromous
hypochlorous
hypoiodous
iodic acid
HONH3+
HOBr
HOCl
HOI
HIO3
5.96
8.63
7.53
10.64
0.77
1.1 × 10–6
2.3 × 10–9
3.0 × 10–8
2.3 × 10–11
1.7 × 10–1
isoleucine
COOH
2.319 (COOH)
9.754 (NH3)
4.80 × 10–3
1.76 × 10–10
2.329 (COOH)
9.747 (NH3)
4.69 × 10–3
1.79 × 10–10
2.04 (COOH); (µ = 0.1 M)
9.08 (α-NH3); (µ = 0.1 M)
10.69 (ε-NH3);(µ = 0.1 M)
9.1 × 10–3
8.3 × 10–10
2.0 × 10–11
CHCH(CH3)CH2CH3
NH3+
leucine
COOH
CHCH2CH(CH3)2
NH3+
lysine
COOH
CHCH2CH2CH2CH2NH3+
NH3+
continued
Acid Dissociation Constants—continued
Compound
Conjugate Acid
maleic acid
HOOC
pKa
COOH
malic acid
OH
HOOCH2C
Ka
1.910
6.332
1.23 × 10–2
4.66 × 10–7
3.459 (COOH)
5.097 (COOH)
3.48 × 10–4
8.00 × 10–6
CHCOOH
malonic acid
HOOCCH2COOH
2.847
5.696
1.42 × 10–3
2.01 × 10–6
methionine
COOH
2.20 (COOH); (µ = 0.1 M)
9.05 (NH3); (µ = 0.1 M)
6.3 × 10–3
8.9 × 10–10
10.64
2.3 × 10–11
4.447
3.57 × 10–5
5.084
8.24 × 10–6
10.28
5.2 × 10–11
10.26
5.5 × 10–11
1.1 (COOH); (T = 20 °C , µ = 1.0 M)
1.650 (COOH); (T = 20 °C)
2.940 (COOH); (T = 20 °C)
10.334 (NH3); (T = 20 °C)
8 × 10–2
2.24 × 10–2
1.15 × 10–3
4.63 × 10–11
2.179
6.62 × 10–3
3.449
3.56 × 10–4
CHCH2CH2SCH3
NH3+
methylamine
CH3NH3+
2-methylaniline
CH3
NH3+
4-methylaniline
NH3+
H3C
2-methylphenol
CH3
OH
4-methylphenol
H3C
nitrilotriacetic acid
OH
CH2COOH
+
HN
CH2COOH
CH2COOH
2-nitrobenzoic acid
COOH
NO2
3-nitrobenzoic acid
COOH
NO2
Compound
Conjugate Acid
pKa
4-nitrobenzoic acid
O2N
Ka
3.442
3.61 × 10–4
7.21
6.2 × 10–8
8.39
4.1 × 10–9
7.15
7.1 × 10–8
3.15
1.252
4.266
4.86
7.1 × 10–4
5.60 × 10–2
5.42 × 10–5
1.38 × 10–5
9.98
1.05 × 10–10
2.20 (COOH)
9.31 (NH3)
6.3 × 10–3
4.9 × 10–10
2.148
7.199
12.35
2.950
5.408
7.11 × 10–3
6.32 × 10–8
4.5 × 10–13
1.12 × 10–3
3.91 × 10–6
11.123
7.53 × 10–12
1.952 (COOH)
10.640 (NH)
1.12 × 10–2
2.29 × 10–11
COOH
2-nitrophenol
OH
NO2
3-nitrophenol
OH
NO2
4-nitrophenol
O2N
nitrous acid
oxalic acid
OH
HNO2
H2C2O4
1,10-phenanthroline
NH+
N
phenol
OH
phenylalanine
COOH
CHCH2C6H5
NH3+
phosphoric acid
H3PO4
phthalic acid
COOH
COOH
piperidine
NH2+
proline
COOH
N
H2+
continued
Acid Dissociation Constants—continued
Compound
Conjugate Acid
propanoic acid
propylamine
CH3CH2COOH
CH3CH2CH2NH3+
pKa
pyridine
Ka
4.874
10.566
1.34 × 10–5
2.72 × 10–11
5.229
5.90 × 10–6
9.30
11.06
5.0 × 10–10
8.7 × 10–12
2.97 (COOH)
13.74 (OH)
1.07 × 10–3
1.8 × 10–14
2.187 (COOH)
9.209 (NH3)
6.50 × 10–3
6.18 × 10–10
4.207
5.636
strong
1.99
1.91
7.18
6.21 × 10–5
2.31 × 10–6
strong
1.0 × 10–2
1.2 × 10–2
6.6 × 10–8
3.036 (COOH)
4.366 (COOH)
9.20 × 10–4
4.31 × 10–5
2.088 (COOH)
9.100 (NH3)
8.17 × 10–3
7.94 × 10–10
0.6
1.6
0.66; (µ = 0.1 M)
7.762
10.715
3 × 10–1
3 × 10–2
2.2 × 10–1
1.73 × 10–8
1.93 × 10–11
NH+
resorcinol
OH
OH
COOH
salicylic acid
OH
serine
COOH
CHCH2OH
NH3+
succinic acid
HOOCCH2CH2COOH
sulfuric acid
H2SO4
sulfurous acid
H2SO3
D-tartaric
acid
OH
HOOC
CH
CH
COOH
OH
threonine
COOH
CHCHOHCH3
NH3+
thiosulfuric acid
H2S2O3
trichloroacetic acid
triethanolamine
triethylamine
Cl3CCOOH
(HOCH2CH2)3NH+
(CH3CH2)3NH+
Compound
Conjugate Acid
pKa
trimethylamine
tris(hydroxymethyl)aminomethane
(TRIS or THAM)
(CH3)3NH+
9.800
1.58 × 10–10
(HOCH2)3CNH3+
8.075
8.41 × 10–9
tryptophan
COOH
2.35 (COOH); (µ = 0.1 M)
9.33 (NH3); (µ = 0.1 M)
4.5 × 10–3
4.7 × 10–10
2.17 (COOH); (µ = 0.1 M)
9.19 (NH3)
10.47 (OH)
6.8 × 10–3
6.5 × 10–10
3.4 × 10–11
2.286 (COOH)
9.718 (OH)
5.18 × 10–3
1.91 × 10–10
Ka
CHCH2
NH3+
tyrosine
N
H
COOH
OH
CHCH2
NH3+
COOH
valine
CHCH(CH3)2
NH3+
Source: All values are from Martell, A. E.; Smith, R. M. Critical Stability Constants, Vol. 1–4. Plenum Press: New York, 1976. Unless otherwise stated, values
are for 25 °C and zero ionic strength. Values in parentheses are considered less reliable.
Metal–Ligand Formation Constants
Acetate
CH3COO–
log K1
Mg2+
1.27
Ca2+
1.18
1.07
Ba2+
Mn2+
1.40
Fe2+
1.40
Co2+
1.46
Ni2+
1.43
log K2
Cu2+
2.22
1.41
Ag+
0.73
–0.09
Zn2+
1.57
Cd2+
1.93
1.22
Pb2+
2.68
1.40
log K3
log K4
log K5
log K6
–0.89
continued
Metal–Ligand Formation Constants—continued
Ammonia
NH3
log K1
log K2
log K3
log K4
Ag+
3.31
3.91
Co2+ (T = 20 °C)
1.99
1.51
0.93
0.64
0.06
–0.74
Ni2+
2.72
2.17
1.66
1.12
0.67
–0.03
Cu2+
4.04
3.43
2.80
1.48
Zn2+
2.21
2.29
2.36
2.03
Cd2+
2.55
2.01
1.34
0.84
log K1
log K2
log K3
log K4
Chloride
Cl–
Cu2+
0.40
Fe3+
1.48
Ag+ (µ = 5.0 M)
3.70
1.92
0.78
–0.3
Zn2+
0.43
0.18
–0.11
–0.3
Cd2+
Pb2+
1.98
1.59
1.62
0.21
–0.2
–0.1
–0.7
–0.3
log K1
log K2
Cyanide
CN–
log K5
log K6
log K5
log K6
log K5
log K6
0.65
log K3
log K4
Fe2+
35.4 (β6)
Fe3+
Ag+
43.6 (β6)
20.48 (β2)
0.92
Zn2+
11.07 (β2)
4.98
3.57
Cd2+
6.01
5.11
4.53
2.27
Hg2+
17.00
15.75
3.56
2.66
Ni2+
30.22 (β4)
Ethylenediamine
H2NCH2CH2NH2
log K1
log K2
log K3
Ni2+
7.38
6.18
4.11
Cu2+
10.48
9.07
Ag+ (T = 20 °C , µ = 0.1 M)
4.70
3.00
Zn2+
Cd2+
5.66
5.41
4.98
4.50
log K4
log K5
log K6
3.25
2.78
EDTA
–
CH2COO–
OOCH2C
NCH2CH2N
–OOCH
2C
CH2COO–
log K1
Mg2+ (T = 20 °C, µ = 0.1 M)
8.79
Ca2+ (T = 20 °C, µ = 0.1 M)
10.69
Ba2+ (T = 20 °C, µ = 0.1 M)
7.86
Bi3+
(T = 20 °C, µ = 0.1 M)
Co2+ (T = 20 °C, µ = 0.1 M)
27.8
16.31
Ni2+ (T = 20 °C, µ = 0.1 M)
18.62
Cu2+ (T = 20 °C, µ = 0.1 M)
18.80
log K2
log K3
log K4
log K5
log K6
EDTA
–
CH2COO–
OOCH2C
NCH2CH2N
–OOCH
2C
CH2COO–
log K1
Cr3+ (T = 20 °C, µ = 0.1 M)
(23.4)
Fe3+ (T = 20 °C, µ = 0.1 M)
25.1
Ag+ (T = 20 °C, µ = 0.1 M)
(T = 20 °C, µ = 0.1 M)
16.50
16.46
Hg2+ (T = 20 °C, µ = 0.1 M)
21.7
Pb2+ (T = 20 °C, µ = 0.1 M)
18.04
Al3+ (T = 20 °C, µ = 0.1 M)
16.3
Fluoride
F–
log K3
log K4
log K5
log K6
7.32
Cd2+ (T = 20 °C, µ = 0.1 M)
Zn2+
log K2
log K1
log K2
log K3
log K4
log K5
log K6
6.11
5.01
3.88
3.0
1.4
0.4
log K1
log K2
log K3
log K4
log K5
log K6
Al3+
9.01
(9.69)
(8.3)
6.0
Co2+
4.3
4.1
1.3
0.5
–0.4
log K5
log K6
log K5
log K6
Al3+ (µ = 0.5 M)
Hydroxide
OH–
Fe2+
4.5
(2.9)
2.6
Fe3+
11.81
10.5
12.1
Ni2+
4.1
3.9
3
Pb2+
6.3
4.6
3.0
Zn2+
5.0
(6.1)
2.5
log K1
log K2
log K3
6.58
(5.12)
(1.4)
Iodide
I–
Ag+ (T = 18 °C)
(1.2)
log K4
Cd2+
2.28
1.64
1.08
1.0
Pb2+
1.92
1.28
0.7
0.6
log K1
log K2
log K3
logK4
Nitriloacetate
CH2COO–
N
CH2COO–
CH2COO–
Mg2+ (T = 20 °C, µ = 0.1 M)
5.41
Ca2+ (T = 20 °C, µ = 0.1 M)
6.41
Ba2+
(T = 20 °C, µ = 0.1 M)
Mn2+ (T = 20 °C, µ = 0.1 M)
4.82
7.44
Fe2+ (T = 20 °C, µ = 0.1 M)
8.33
Co2+ (T = 20 °C, µ = 0.1 M)
10.38
Ni2+ (T = 20 °C, µ = 0.1 M)
11.53
Cu2+ (T = 20 °C, µ = 0.1 M)
12.96
Fe3+ (T = 20 °C, µ = 0.1 M)
15.9
Zn2+
(T = 20 °C, µ = 0.1 M)
10.67
Cd2+ (T = 20 °C, µ = 0.1 M)
9.83
Pb2+ (T = 20 °C, µ = 0.1 M)
11.39
continued
Metal–Ligand Formation Constants—continued
Oxalate
C2O42–
log K1
log K2
Ca2+ (µ = 1 M)
Fe2+ (µ = 1 M)
1.66
3.05
1.03
2.10
Co2+
4.72
2.28
Ni2+
5.16
Cu2+
6.23
Fe3+ (µ = 0.5 M)
7.53
6.11
Zn2+
4.87
2.78
log K1
log K2
log K3
logK4
log K5
log K6
logK4
log K5
log K6
logK4
log K5
log K6
logK4
log K5
log K6
4.04
4.85
1,10-Phenanthroline
NH+
N
Fe2+
Mn2+
log K3
20.7 (β3)
4.0
3.3
3.0
Co2+ (µ = 0.1 M)
(µ = 0.1 M)
7.08
6.64
6.08
Ni2+ (µ = 0.1 M)
8.6
8.1
Fe3+
7.6
13.8 (β3)
Ag+ (µ = 0.1 M)
5.02
7.04
Zn2+
6.2
(5.9)
(5.2)
Thiosulfate
S2O32–
log K1
log K2
log K3
Ag+ (T = 20 °C)
8.82
4.85
0.53
log K1
log K2
log K3
Thiocyanate
SCN–
Mn2+
Fe2+
1.23
1.31
Co2+
1.72
Ni2+
1.76
Cu2+
2.33
Fe3+
3.02
Ag+
4.8
3.43
1.27
0.2
Zn2+
1.33
0.58
0.09
–0.4
Cd2+
1.89
0.89
0.02
–0.5
Hg2+
17.26 (β2)
2.71
1.83
Source: All values are from Martell, A. E.; Smith, R. M. Critical Stability Constants, Vol. 1–4, Plenum Press: New York, 1976. Unless otherwise stated, values
are for 25 °C and zero ionic strength. Values in parentheses are considered less reliable.