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Appendix 10: Solubility Products

The following table provides pKsp and Ksp values for selected compounds, organized by the anion. 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 oC and zero ionic strength.

Bromide (Br)

pKsp

Ksp

CuBr

8.3

5.×10–9

AgBr

12.30

5.0×10–13

Hg2Br2

22.25

5.6×10–13

HgBr2 (μ = 0.5 M)

18.9

1.3×10–19

PbBr2 (μ = 4.0 M)

5.68 2.1×10–6

Carbonate (CO32–)

pKsp

Ksp

MgCO3

7.46

3.5×10–8

CaCO3 (calcite)

8.35

4.5×10–9

CaCO3 (aragonite)

8.22

6.0×10–9

SrCO3

9.03

9.3×10–10

BaCO3

8.30

5.0×10–9

MnCO3

9.30

5.0×10–10

FeCO3

10.68

2.1×10–11

CoCO3

9.98

1.0×10–10

NiCO3

6.87

1.3×10–7

Ag2CO3

11.09

8.1×10–12

Hg2CO3

16.05

8.9×10–17

ZnCO3

10.00

1.0×10–10

CdCO3

13.74

1.8×10–14

PbCO3 13.13

7.4×10–14

Chloride (Cl)

pKsp

Ksp

CuCl

6.73

1.9×10–7

AgCl

9.74

1.8×10–10

Hg2Cl2

17.91

1.2×10–18

PbCl2

4.78

2.0×10–19

Chromate (CrO42–)

pKsp

Ksp

BaCrO4

9.67

2.1×10–10

CuCrO4

5.44

3.6×10–6

Ag2CrO4

11.92

1.2×10–12

Hg2CrO4

8.70

2.0×10–9

Cyanide (CN)

pKsp

Ksp

AgCN

15.66

2.2×10–16

Zn(CN)2 (μ = 3.0 M)

15.5

3.×10–16

Hg2(CN)2

39.3

5.×10–40

Ferrocyanide [Fe(CN)64–]

pKsp

Ksp

Zn2[Fe(CN)6]

15.68

2.1×10–16

Cd2[Fe(CN)6]

17.38

4.2×10–18

Pb2[Fe(CN)6]

18.02

9.5×10–19

Fluoride (F)

pKsp

Ksp

MgF2

8.18

6.6×10–9

CaF2

10.41

3.9×10–11

SrF2

8.54

2.9×10–9

BaF2

5.76

1.7×10–6

PbF2 7.44

3.6×10–8

Hydroxide (OH)

pKsp

Ksp

Mg(OH)2

11.15

7.1×10–12

Ca(OH)2

5.19

6.5×10–6

Ba(OH)2•8H2O

3.6

3.×10–4

La(OH)3

20.7

2.×10–21

Mn(OH)2

12.8

1.6×10–13

Fe(OH)2

15.1

8.×10–16

Co(OH)2

14.9

1.3×10–15

Ni(OH)2

15.2

6.×10–16

Cu(OH)2

19.32

4.8×10–20

Fe(OH)3

38.8

1.6×10–39

Co(OH)3 (T = 19oC)

44.5

3.×10–45

Ag2O (+ H2O ⇋ 2Ag+ + 2OH)

15.42

3.8×10–16

Cu2O (+ H2O ⇋ 2Cu+ + 2OH) 29.4 4.×10–30
Zn(OH)2 (amorphous) 15.52 3.0×10–16
Cd(OH)2 (β) 14.35 4.5×10–15
HgO (red) (+ H2O ⇋ Hg2+ + 2OH) 25.44 3.6×10–26
SnO (+ H2O ⇋ Sn2+ + 2OH) 26.2 6.×10–27
PbO (yellow) (+ H2O ⇋ Pb2+ + 2OH) 15.1 8.×10–16
Al(OH)3 (α) 33.5 3.×10–34

Iodate (IO3)

pKsp

Ksp

Ca(IO3)2

6.15

7.1×10–7

Ba(IO3)2

8.81

1.5×10–9

AgIO3

7.51

3.1×10–8

Hg2(IO3)2

17.89

1.3×10–18

Zn(IO3)2

5.41

3.9×10–6

Cd(IO3)2

7.64

2.3×10–8

Pb(IO3)2

12.61 2.5×10–13

Iodide (I)

pKsp

Ksp

AgI

16.08

8.3×10–17

Hg2I2

28.33

4.7×10–29

HgI2 (μ = 0.5 M)

27.95

1.1×10–28

PbI2

8.10 7.9×10–9

Oxalate (C2O42–)

pKsp Ksp

CaC2O4 (μ = 0.1 M, T = 20 oC)

7.9

1.3×10–8

BaC2O4 (μ = 0.1 M, T = 20 oC)

6.0

1.×10–6

SrC2O4 (μ = 0.1 M, T = 20 oC)

6.4 4.×10–7

Phosphate (PO43–)

pKsp

Ksp

Fe3(PO4)2•8H2O

36.0

1.×10–36

Zn3(PO4)2•4H2O

35.3

5.×10–36

Ag3PO4

17.55

2.8×10–18

Pb3(PO4)2 (T = 38 oC)

43.55

3.0×10–44

Sulfate (SO42–)

pKsp

Ksp

CaSO4

4.62

2.4×10–5

SrSO4

6.50

3.2×10–7

BaSO4

9.96

1.1×10–10

Ag2SO4

4.83

1.5×10–5

Hg2SO4

6.13

7.4×10–7

PbSO4

7.79

1.6×10–8

Sulfide (S2–)

pKsp Ksp

MnS (green)

13.5

3.×10–14

FeS

18.1

8.×10–19

CoS (β)

25.6

3.×10–26

NiS (γ)

26.6

3.×10–27

CuS

36.1

8.×10–37

Cu2S

48.5

3.×10–49

Ag2S

50.1

8.×10–51

ZnS (α)

24.7

2.×10–25

CdS

27.0

1.×10–27

Hg2S (red)

53.3

5.×10–54

PbS

27.5

3.×10–28

Thiocyanate (SCN)

pKsp Ksp

CuSCN (μ = 5.0 M)

13.40

4.0×10–14

AgSCN

11.97

1.1×10–12

Hg2(SCN)2

19.52

3.0×10–20

Hg(SCN)2 (μ = 1.0 M)

19.56

2.8×10–20