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E3. Solubility Constants for Compounds at 25°C

Although all compounds have a characteristic solubility in water at a given temperature, some families of compounds are more soluble than others and it is useful to know certain general rules of solubility. We call any substance the solubility of which is less than 0.01 mol/L insoluble. If its solubility is greater than 0.1 mol/L, we call it soluble. If its solubility is between 0.01 and 0.1 mol/L, we say that it is slightly soluble. The following solubility rules can be used to determine solubilities in water, with the disclaimer that they don't always hold, nor do they include every ion which is in common use, but they are good to have nearby when needed:

  1. All sodium, potassium, and ammonium salts are soluble.
  2. All nitrates, acetates and perchlorates are soluble.
  3. All silver, lead and mercury(I) salts are insoluble.
  4. All chlorides, bromides and iodides are soluble.
  5. All carbonates, sulfides, oxides and hydroxides are insoluble.
  6. All sulfates are soluble except strontium sulfate and barium sulfate.
Compound Name Compound Formula Ksp
Aluminum phosphate AlPO4 9.84 × 10−21
Barium bromate Ba(BrO3)2 2.43 × 10−4
Barium carbonate BaCO3 2.58 × 10−9
Barium chromate BaCrO4 1.17 × 10−10
Barium fluoride BaF2 1.84 × 10−7
Barium iodate Ba(IO3)2 4.01 × 10−9
Barium nitrate Ba(NO3)2 4.64 × 10−3
Barium sulfate BaSO4 1.08 × 10−10
Barium sulfite BaSO3 5.0 × 10−10
Beryllium hydroxide Be(OH)2 6.92 × 10−22
Bismuth arsenate BiAsO4 4.43 × 10−10
Bismuth iodide BiI3 7.71 × 10−19
Cadmium carbonate CdCO3 1.0 × 10−12
Cadmium fluoride CdF2 6.44 × 10−3
Cadmium hydroxide Cd(OH)2 7.2 × 10−15
Cadmium iodate Cd(IO3)2 2.5 × 10−8
Cadmium phosphate Cd3(PO4)2 2.53 × 10−33
Cadmium sulfide CdS 8.0 × 10−27
Calcium carbonate CaCO3 3.36 × 10−9
Calcium fluoride CaF2 3.45 × 10−11
Calcium hydroxide Ca(OH)2 5.02 × 10−6
Calcium iodate Ca(IO3)2 6.47 × 10−6
Calcium phosphate Ca3(PO4)2 2.07 × 10−33
Calcium sulfate CaSO4 4.93 × 10−5
Cesium perchlorate CsClO4 3.95 × 10−3
Cesium periodate CsIO4 5.16 × 10−6
Cobalt(II) arsenate Co3(AsO4)2 6.80 × 10−29
Cobalt(II) hydroxide Co(OH)2 5.92 × 10−15
Cobalt(II) phosphate Co3(PO4)2 2.05 × 10−35
Copper(I) bromide CuBr 6.27 × 10−9
Copper(I) chloride CuCl 1.72 × 10−7
Copper(I) cyanide CuCN 3.47 × 10−20
Copper(I) iodide CuI 1.27 × 10−12
Copper(I) thiocyanate CuSCN 1.77 × 10−13
Copper(II) arsenate Cu3(AsO4)2 7.95 × 10−36
Copper(II) oxalate CuC2O4 4.43 × 10−10
Copper(II) phosphate Cu3(PO4)2 1.40 × 10−37
Copper(II) sulfide CuS 6.3 × 10−36
Europium(III) hydroxide Eu(OH)3 9.38 × 10−27
Gallium(III) hydroxide Ga(OH)3 7.28 × 10−36
Iron(II) carbonate FeCO3 3.13 × 10−11
Iron(II) fluoride FeF2 2.36 × 10−6
Iron(II) hydroxide Fe(OH)2 4.87 × 10−17
Iron(III) hydroxide Fe(OH)3 2.79 × 10−39
Iron(III) sulfide FeS 6.3 × 10−18
Lanthanum iodate La(IO3)3 7.50 × 10−12
Lead(II) bromide PbBr2 6.60 × 10−6
Lead(II) carbonate PbCO3 7.40 × 10−14
Lead(II) chloride PbCl2 1.70 × 10−5
Lead(II) fluoride PbF2 3.3 × 10−8
Lead(II) hydroxide Pb(OH)2 1.43 × 10−20
Lead(II) iodate Pb(IO3)2 3.69 × 10−13
Lead(II) iodide PbI2 9.8 × 10−9
Lead(II)selenite PbSeO4 1.37 × 10−7
Lead(II) sulfate PbSO4 2.53 × 10−8
Lead(II) sulfide PbS 8.0 × 10−28
Lithium carbonate Li2CO3 8.15 × 10−4
Lithium fluoride LiF 1.84 × 10−3
Lithium phosphate Li3PO4 2.37 × 10−11
Magnesium carbonate MgCO3 6.82 × 10−6
Magnesium fluoride MgF2 5.16 × 10−11
Magnesium hydroxide Mg(OH)2 5.61 × 10−12
Magnesium phosphate Mg3(PO4)2 1.04 × 10−24
Manganese(II) carbonate MnCO3 2.24 × 10−11
Manganese(II) iodate Mn(IO3)2 4.37 × 10−7
Mercury(I) bromide Hg2Br2 6.40 × 10−23
Mercury(I) carbonate Hg2CO3 3.6 × 10−17
Mercury(I) chloride Hg2Cl2 1.43 × 10−18
Mercury(I) fluoride Hg2F2 3.10 × 10−6
Mercury(I) iodide Hg2I2 5.2 × 10−29
Mercury(I) oxalate Hg2C2O4 1.75 × 10−13
Mercury(I) sulfate Hg2SO4 6.5 × 10−7
Mercury(I) thiocyanate Hg2(SCN)2 3.2 × 10−20
Mercury(II) bromide HgBr2 6.2 × 10−20
Mercury (II) iodide HgI2 2.9 × 10−29
Mercury(II) sulfide (red) HgS 4 × 10−53
Mercury(II) sulfide (black) HgS 1.6 × 10−52
Neodymium carbonate Nd2(CO3)3 1.08 × 10−33
Nickel(II) carbonate NiCO3 1.42 × 10−7
Nickel(II) hydroxide Ni(OH)2 5.48 × 10−16
Nickel(II) iodate Ni(IO3)2 4.71 × 10−5
Nickel(II) phosphate Ni3(PO4)2 4.74 × 10−32
Palladium(II) thiocyanate Pd(SCN)2 4.39 × 10−23
Potassium hexachloroplatinate K2PtCl6 7.48 × 10−6
Potassium perchlorate KClO4 1.05 × 10−2
Potassium periodate KIO4 3.71 × 10−4
Praseodymium hydroxide Pr(OH)3 3.39 × 10−24
Rubidium perchlorate RbClO4 3.00 × 10−3
Scandium fluoride ScF3 5.81 × 10−24
Scandium hydroxide Sc(OH)3 2.22 × 10−31
Silver(I) acetate AgCH3CO2 1.94 × 10−3
Silver(I) arsenate Ag3AsO4 1.03 × 10−22
Silver(I) bromate AgBrO3 5.38 × 10−5
Silver(I) bromide AgBr 5.35 × 10−13
Silver(I) carbonate Ag2CO3 8.46 × 10−12
Silver(I) chloride AgCl 1.77 × 10−10
Silver(I) chromate Ag2CrO4 1.12 × 10−12
Silver(I) cyanide AgCN 5.97 × 10−17
Silver(I) iodate AgIO3 3.17 × 10−8
Silver(I) iodide AgI 8.52 × 10−17
Silver(I) oxalate Ag2C2O4 5.40 × 10−12
Silver(I) phosphate Ag3PO4 8.89 × 10−17
Silver(I) sulfate Ag2SO4 1.20 × 10−5
Silver(I) sulfide Ag2S 6.3 × 10−50
Silver(I) sulfite Ag2SO3 1.50 × 10−14
Silver(I) thiocyanate AgSCN 1.03 × 10−12
Strontium arsenate Sr3(AsO4)2 4.29 × 10−19
Strontium carbonate SrCO3 5.60 × 10−10
Strontium fluoride SrF2 4.33 × 10−9
Strontium iodate Sr(IO3)2 1.14 × 10−7
Strontium sulfate SrSO4 3.44 × 10−7
Thallium(I) bromate TlBrO3 1.10 × 10−4
Thallium(I) bromide TlBr 3.71 × 10−6
Thallium(I) chloride TlCl 1.86 × 10−4
Thallium(I) chromate Tl2CrO4 8.67 × 10−13
Thallium(I) iodate TlIO3 3.12 × 10−6
Thallium(I) iodide TlI 5.54 × 10−8
Thallium(I) thiocyanate TlSCN 1.57 × 10−4
Thallium(III) hydroxide Tl(OH)3 1.68 × 10−44
Tin(II) hydroxide Sn(OH)2 5.45 × 10−27
Tin(II) sulfide SnS 1.0 × 10−25
Yttrium carbonate Y2(CO3)3 1.03 × 10−31
Yttrium fluoride YF3 8.62 × 10−21
Yttrium hydroxide Y(OH)3 1.00 × 10−22
Yttrium iodate Y(IO3)3 1.12 × 10−10
Zinc arsenate Zn3(AsO4)2 2.8 × 10−28
Zinc carbonate ZnCO3 1.46 × 10−10
Zinc fluoride ZnF2 3.04 × 10−2
Zinc hydroxide Zn(OH)2 3 × 10−17
Zinc selenide ZnSe 3.6 × 10−26
Zinc sulfide (wurtzite) ZnS 1.6 × 10−24
Zinc sulfide (sphalerite) ZnS 2.5 × 10−22