Solubility products (25 °C)

Solubility products of common sparingly soluble salts, their molar solubilities in pure water and the observed colours of the precipitates, plus acid solubility products of metal sulfides. Every precipitation calculation in the precipitation and complex-ion unit uses this table.


Silver chloride	$\ce{AgCl}$	AB	9.74	1.8 × 10⁻¹⁰	1.3 × 10⁻⁵	white, curdy	Martell & Smith
Silver bromide	$\ce{AgBr}$	AB	12.30	5.0 × 10⁻¹³	7.1 × 10⁻⁷	pale yellow (cream)	Martell & Smith
Silver iodide	$\ce{AgI}$	AB	16.08	8.3 × 10⁻¹⁷	9.1 × 10⁻⁹	yellow	Martell & Smith
Silver chromate	$\ce{Ag2CrO4}$	A2B	11.92	1.2 × 10⁻¹²	6.7 × 10⁻⁵	brick red	Martell & Smith
Lead(II) chloride	$\ce{PbCl2}$	AB2	4.78	1.7 × 10⁻⁵	0.016	white	Martell & Smith
Lead(II) iodide	$\ce{PbI2}$	AB2	8.10	7.9 × 10⁻⁹	0.0013	bright yellow	Martell & Smith
Lead(II) sulfate	$\ce{PbSO4}$	AB	7.79	1.6 × 10⁻⁸	1.3 × 10⁻⁴	white	Martell & Smith
Lead(II) chromate	$\ce{PbCrO4}$	AB	12.55	2.8 × 10⁻¹³	5.3 × 10⁻⁷	yellow	Lange’s Handbook (±1 order of magnitude)
Mercury(I) chloride	$\ce{Hg2Cl2}$	AB2	17.91	1.2 × 10⁻¹⁸	6.8 × 10⁻⁷	white	Martell & Smith
Barium sulfate	$\ce{BaSO4}$	AB	9.96	1.1 × 10⁻¹⁰	1.0 × 10⁻⁵	white	Martell & Smith
Barium chromate	$\ce{BaCrO4}$	AB	9.67	2.1 × 10⁻¹⁰	1.5 × 10⁻⁵	pale yellow	Martell & Smith
Calcium carbonate (calcite)	$\ce{CaCO3}$	AB	8.35	4.5 × 10⁻⁹	6.7 × 10⁻⁵	white	Martell & Smith
Calcium fluoride	$\ce{CaF2}$	AB2	10.41	3.9 × 10⁻¹¹	2.1 × 10⁻⁴	white	Martell & Smith
Calcium sulfate	$\ce{CaSO4}$	AB	4.62	2.4 × 10⁻⁵	0.0049	white	Martell & Smith
Calcium oxalate	$\ce{CaC2O4}$	AB	7.90	1.3 × 10⁻⁸	1.1 × 10⁻⁴	white	Martell & Smith
Strontium sulfate	$\ce{SrSO4}$	AB	6.50	3.2 × 10⁻⁷	5.6 × 10⁻⁴	white	Martell & Smith
Magnesium hydroxide	$\ce{Mg(OH)2}$	AB2	11.15	7.1 × 10⁻¹²	1.2 × 10⁻⁴	white, gelatinous	Martell & Smith
Calcium hydroxide	$\ce{Ca(OH)2}$	AB2	5.19	6.5 × 10⁻⁶	0.012	white	Martell & Smith
Manganese(II) hydroxide	$\ce{Mn(OH)2}$	AB2	12.80	1.6 × 10⁻¹³	3.4 × 10⁻⁵	off-white (browns in air)	Martell & Smith
Iron(II) hydroxide	$\ce{Fe(OH)2}$	AB2	15.10	7.9 × 10⁻¹⁶	5.8 × 10⁻⁶	pale green (darkens in air)	Martell & Smith
Cobalt(II) hydroxide	$\ce{Co(OH)2}$	AB2	14.90	1.3 × 10⁻¹⁵	6.8 × 10⁻⁶	pink	Martell & Smith
Nickel(II) hydroxide	$\ce{Ni(OH)2}$	AB2	15.20	6.3 × 10⁻¹⁶	5.4 × 10⁻⁶	apple green	Martell & Smith
Copper(II) hydroxide	$\ce{Cu(OH)2}$	AB2	19.32	4.8 × 10⁻²⁰	—	pale blue	Martell & Smith
Zinc hydroxide	$\ce{Zn(OH)2}$	AB2	15.52	3.0 × 10⁻¹⁶	4.2 × 10⁻⁶	white	Martell & Smith
Cadmium hydroxide	$\ce{Cd(OH)2}$	AB2	14.35	4.5 × 10⁻¹⁵	1.0 × 10⁻⁵	white	Martell & Smith
Aluminium hydroxide	$\ce{Al(OH)3}$	AB3	33.50	3.2 × 10⁻³⁴	—	white, gelatinous	Martell & Smith
Iron(III) hydroxide	$\ce{Fe(OH)3}$	AB3	38.80	1.6 × 10⁻³⁹	—	red-brown	Martell & Smith
MnS (acid solubility product Kspa)	$\ce{MnS}$	MS + 2H⁺	−10.48	3.0 × 10¹⁰	—	salmon pink	Petrucci; Myers 1986
FeS (acid solubility product Kspa)	$\ce{FeS}$	MS + 2H⁺	−2.78	600	—	black	Petrucci; Myers 1986
NiS (acid solubility product Kspa)	$\ce{NiS}$	MS + 2H⁺	0.10	0.8	—	black	Petrucci; Myers 1986
CdS (acid solubility product Kspa)	$\ce{CdS}$	MS + 2H⁺	6.10	8.0 × 10⁻⁷	—	yellow	Petrucci; Myers 1986
PbS (acid solubility product Kspa)	$\ce{PbS}$	MS + 2H⁺	6.52	3.0 × 10⁻⁷	—	black	Petrucci; Myers 1986
CuS (acid solubility product Kspa)	$\ce{CuS}$	MS + 2H⁺	15.22	6.0 × 10⁻¹⁶	—	black	Petrucci; Myers 1986

“s in pure water” uses s = (Ksp/xˣyʸ)^(1/(x+y)), ignoring hydrolysis and complexation; for extremely insoluble hydroxides such as Fe(OH)₃, Al(OH)₃ and Cu(OH)₂ the OH⁻ from water itself dominates and the formula is meaningless, so it is left blank. The sulfide rows give acid solubility products Kspa (MS + 2H⁺ ⇌ M²⁺ + H₂S), whose literature values scatter widely.

Sources

A. E. Martell & R. M. Smith, Critical Stability Constants, Vol. 4 (Plenum, 1976), 25 °C and I = 0, as tabulated in D. Harvey, Analytical Chemistry 2.1, Appendix 10 (also used by D. C. Harris, Quantitative Chemical Analysis, Appendix F).
W. M. Haynes (ed.), CRC Handbook of Chemistry and Physics, 84th–97th eds.: solubility product constants.
J. A. Dean (ed.), Lange’s Handbook of Chemistry, 15th ed. (1999): PbCrO₄.
R. H. Petrucci et al., General Chemistry (Kspa of metal sulfides), after R. J. Myers, J. Chem. Educ. 63, 687 (1986).
Precipitate colours: G. Svehla, Vogel’s Qualitative Inorganic Analysis, 7th ed. (1996); N. N. Greenwood & A. Earnshaw, Chemistry of the Elements, 2nd ed. (1997).

Sources

Used in these lessons