The solubility of a compound in water is the maximum amount of that compound that can dissolve in a given volume of water at a specific temperature. The solubility of a compound can vary significantly depending on the temperature of the water.
Generally, as the temperature of the water increases, the solubility of most compounds also increases. This is because the increased thermal energy helps to overcome the intermolecular forces holding the solute particles together, allowing them to more easily disperse into the water.
However, there are some exceptions to this general trend. For example, the solubility of gases in water typically decreases as the temperature increases, due to the reduced ability of the water to "hold" the gas molecules.
The specific relationship between temperature and solubility can be quite complex and depends on the nature of the compound and its interactions with water. Some key factors that influence solubility include:
- Polarity and charge of the solute molecules
- Hydrogen bonding interactions
- Size and shape of the solute molecules
- Presence of other dissolved substances (salts, etc.)
Inorganic compounds are substances that do not contain carbon-hydrogen bonds, and they can exhibit a wide range of solubility behavior in water. The table below gives reference values for the solubility of common inorganic compounds and salts in water at six temperatures ranging from 0 degrees Celsius to 100 degrees Celsius.
| Inorganic Compounds | Chemical Formula | Solubility in g/100 g H2O at °C | |||||
| 0 | 20 | 40 | 60 | 80 | 100 | ||
| Aluminum ammonium sulfate dodecahydrate | AlNH4(SO4)2·12H2O | 2.6 | 6.59 | 12.36 | 21.1 | 35.2 | 109.2 (95 °C) |
| Aluminum chloride hexahydrate | AlCl3·6H2O | 44.9 | 45.6 | 46.3 | 47 | 47.7 | – |
| Aluminum nitrate nonahydrate | Al(NO3)3·9H2O | 61 | 75.44 | 89 | 108 | – | – |
| Aluminum potassium sulfate dodecahydrate | AlK(SO4)2·12H2O | 2.96 | 6.01 | 13.6 | 33.3 | 72 | 109(90 °C) |
| Aluminum sulfate octadecahydrate | Al2(SO4)3·18H2O | 31.2 | 36.44 | 45.6 | 58 | 73 | 89 |
| Ammonium bromide | NH4Br | 60.6 | 75.5 | 91.1 | 107.8 | 126.7 | 145.6 |
| Ammonium chloride | NH4Cl | 29.7 | 37.56 | 46 | 55.3 | 65.6 | 77.3 |
| Ammonium dihydrogen phosphate | NH4H2PO4 | 22.7 | 36.8 | 56.7 | 82.9 | 120.7 | 174 |
| Ammonium hydrogen carbonate | NH4HCO3 | 11.9 | 21.22 | 36.6 | 59.2 | 109.2 | 355 |
| di-Ammonium hydrogen phosphate | (NH4)2HPO4 | 57.5 | 68.6 | 81.8 | 97.6 | -115.5 | – |
| Ammonium iron(II) sulfate hexahydrate | (NH4)2Fe(SO4)2·6H2O | 17.8 | 26.9 | 38.5 | 53.4 | 73 | – |
| Ammonium mono-vanadate | NH4VO3 | – | 4.8 | 13.2 | – | – | – |
| Ammonium nitrate | NH4NO3 | 118.5 | 187.7 | 283 | 415 | 610 | 1000 |
| Ammonium sulfate | (NH4)2SO4 | 70.4 | 75.44 | 81.2 | 87.4 | 94.1 | 102 |
| Ammonium thiocyanate | NH4SCN | 115 | 163 | 235 | 347 | -525 | – |
| Antimony(III) chloride | SbCl3 | 601.6 | 931.5 | 1368 | 4531 | – | – |
| Barium acetate | Ba(CH3COO)2 | 58 | 72 | 79 | 74 | 74 | 74 |
| Barium chloride dihydrate | BaCl2·2H2O | 30.7 | 35.7 | 40.8 | 46.4 | 52.5 | 58.7 |
| Barium hydroxide octahydrate | Ba(OH)2·8H2O | 1.5 | 3.48 | 8.2 | 21 | – | – |
| Barium nitrate | Ba(NO3)2 | 4.95 | 9.06 | 14.4 | 20.3 | 27.2 | 34.2 |
| di-Boron trioxide | B2O3 | 1.1 | 2.2 | 4 | 6.2 | 9.5 | 15.7 |
| Boric acid | H3BO3 | 2.66 | 5.042 | 8.7 | 14.8 | 23.6 | 39.7 |
| Cadmium sulfate octahydrate | 3CdSO4·8H2O | 75.75 | 76.69 | 79.26 | 81.9 | 84.6 | – |
| Calcium chloride dihydrate | CaCl2·2H2O | – | – | 128.1 | 136.8 | 147 | 159 |
| Calcium nitrate tetrahydrate | Ca(NO3)2·4H2O | 101 | 129.39 | 196 | – | – | – |
| Calcium sulfate dihydrate | CaSO4·2H2O | 0.176 | 0.36 | 0.2122 | 0.2047 | 0.1966 | 0.1619 |
| Cesium chloride | CsCl | 161 | 187 | 208 | 230 | 250 | 271 |
| Cesium nitrate | CsNO3 | 9.3 | 23 | 47.2 | 83.8 | 134 | 197 |
| Chromium(VI) oxide | CrO3 | 163 | 166.72 | 171 | 176 | 189 | 199 |
| Cobalt chloride hexahydrate | CoCl2·6H2O | 83.5 | 100 | 126 | 169.5 (56 °C) | ||
| Cobalt nitrate hexahydrate | Co(NO3)2·6H2O | – | – | 50 | – | ||
| Cobalt sulfate heptahydrate | CoSO4·7H2O | 25.5 | 36.26 | 49.9 | – | – | – |
| Copper(I) chloride | CuCl | – | 1.52 (25 °C) | – | – | – | – |
| Copper(II) chloride dihydrate | CuCl2·2H2O | 70.65 | 77 | 83.8 | 91.2 | 99.2 | 107.9 |
| Copper(II) nitrate trihydrate | Cu(NO3)2·3H2O | – | – | 160 | 179 | 208 | -257 |
| Copper (II) sulfate anhydrous | CuSO4 | 25.5 | 36.2 | 48 | 60 | 70 | 83 |
| Copper(II) sulfate pentahydrate | CuSO4·5H2O | 14.8 | 20.77 | 29 | 39.1 | 53.6 | 73.6 |
| Iron(III) chloride hexahydrate | FeCl3·6H2O | 74.5 | 91.94 | – | – | – | – |
| Iron(II) chloride tetrahydrate | FeCl2·4H2O | – | 62.35 | 68.6 | 78.3 | – | – |
| Iron(II) sulfate heptahydrate | FeSO4·7H2O | 15.65 | 26.58 | 40.3 | 47.6 (50 °C) | – | – |
| Iron(II) sulfate monohydrate | FeSO4·H2O | – | – | – | – | 43.8 | -31.6 |
| Iron (III) chloride hexahydrate | FeCl3·6H2O | 74.5 | 91.94 | – | – | – | – |
| Lead chloride | PbCl2 | 0.6728 | 0.99 | 1.45 | 1.98 | 2.62 | 3.31 |
| Lead nitrate | Pb(NO3)2 | 36.4 | 52.22 | 69.4 | 88 | 107.5 | 127.3 |
| Lithium carbonate | Li2CO3 | – | 1.33 | – | – | – | – |
| Lithium chloride monohydrate | LiCl·H2O | – | 82.82 | 90.4 | 100 | 113 | -127.5 |
| Lithium sulfate monohydrate | LiSO4·H2O | 36.2 | 34.8 | 33.5 | 32.3 | 31.5 | 31 |
| Magnesium chloride hexahydrate | MgCl2·6H2O | 52.8 | 54.57 | 57.5 | 60.7 | 65.87 | 72.7 |
| Magnesium nitrate hexahydrate | Mg(NO3)2·6H2O | 63.9 | 70.07 | 81.8 | 93.7 | – | – |
| Magnesium sulfate heptahydrate | MgSO4·7H2O | 30.05 (10 °C) | 35.6 | 45.4 | – | – | – |
| Manganese(II) chloride tetrahydrate | MnCl2·4H2O | 63.6 | 73.62 | 88.7 | -106 (58.1 °C) | – | – |
| Manganese(II) chloride dihydrate | MnCl2·2H2O | – | – | – | – | 110.5 | 115 |
| Manganese(II) sulfate monohydrate | MnSO4·H2O | – | – | 60 | 58.6 | 45.5 | 35.5 |
| Mercury(II) bromide | HgBr2 | – | 0.62 (25 °C) | -0.96 | 1.67 | 2.77 | 4.9 |
| Mercury(II) chloride | HgCl2 | 4.29 | 6.61 | 9.6 | 13.9 | 24.2 | 54.1 |
| Nickel chloride hexahydrate | NiCl2·6H2O | 51.7 | 55.3 | – | – | – | – |
| Nickel nitrate hexahydrate | Ni(NO3)2·6H2O | 79.2 | 94.1 | 118.8 | – | – | – |
| Nickel sulfate hexahydrate | Ni2SO4·6H2O | – | – | – | 57 | – | – |
| Potassium bromate | KBrO3 | 3.1 | 6.8 | 13.1 | 22 | 33.9 | 49.7 |
| Potassium bromide | KBr | 54 | 65.85 | 76.1 | 85.9 | 95.3 | 104.9 |
| Potassium carbonate | K2CO3 | 105.5 | 111.5 | 117 | 127 | 140 | 156 |
| Potassium chlorate | KClO3 | 3.3 | 7.3 | 14.5 | 25.9 | 39.7 | 56.2 |
| Potassium chloride | KCl | 28.15 | 34.24 | 40.3 | 45.6 | 51 | 56.2 |
| Potassium chromate | K2CrO4 | 59 | 63.68 | 67 | 70.9 | 75.1 | 79.2 |
| Potassium cyanide | KCN | -63 | 71.6 (25 °C) | – | 81 (50 °C) | -95 (75 °C) | 122 (103.3 °C) |
| Potassium dichromate | K2Cr2O7 | 4.68 | 12.49 | 26.3 | 45.6 | 73 | 103 |
| Potassium dihydrogen phosphate | KH2PO4 | 14.3 | 22.7 | 33.9 | 48.6 | 68 | – |
| Potassium disulfite | K2S2O5 | 27.5 | 44.9 | 63.9 | 85 | 108 | 133 |
| Potassium hexachloroplatinate(IV) | K2[Pt(Cl)6] | 0.74 | 1.1 | 1.7 | 2.6 | 3.8 | 5.2 |
| Potassium hexacyanoferrate(II) trihydrate | K4[Fe(CN)6]·3H2O | 15 | 28.87 | 42.7 | 56 | 68.9 | -82.7 |
| Potassium hexacyanoferrate(III) | K3[Fe(CN)6] | 29.9 | 46 | 59.5 | 70.9 | 81.8 | 91.6 |
| Potassium hydrogen carbonate | KHCO3 | 22.6 | 33.3 | 45.3 | 60 | – | – |
| di-Potassium hydrogen phosphate trihydrate | K2HPO4·3H2O | – | 159 | 212.5 | – | – | – |
| di-Potassium hydrogen phosphate anhydrous | K2HPO4 | – | – | – | 266 | – | – |
| Potassium hydrogen sulfate | KHSO4 | 36.3 | 51.4 | 76.3 | – | – | 121.6 |
| Potassium hydroxide monohydrate | KOH·H2O | – | – | 136.4 | 147 | 160 | 178 |
| Potassium iodate | KlO3 | 4.7 | 8.11 | 12.9 | 18.5 | 24.8 | 32.3 |
| Potassium iodide | Kl | 127.8 | 144.51 | 161 | 176.2 | 191.5 | 208 |
| Potassium nitrate | KNO3 | 13.25 | 31.66 | 63.9 | 109.9 | 169 | 245.2 |
| di-Potassium oxalate monohydrate | K2C2O4·H2O | – | 35.88 | – | – | – | – |
| Potassium perchlorate | KClO4 | 0.76 | 1.73 | 3.63 | 7.18 | 13.38 | 22.2 |
| Potassium permanganate | KMnO4 | 2.83 | 6.43 | 12.56 | 22.4 | – | – |
| Potassium peroxodisulfate | K2S2O8 | 0.18 | 0.47 | 1.1 | – | – | – |
| Potassium sulfate | K2SO4 | 7.33 | 11.11 | 14.79 | 18.2 | 21.29 | 24.1 |
| Potassium thiocyanate | KSCN | 177 | 218 | – | – | – | – |
| Rubidium chloride | RbCl | 70.6 | 83.6 | – | – | – | 128 |
| Silver nitrate | AgNO3 | 115 | 219.2 | 334.8 | 471 | 652 | 1024 |
| Silver sulfate | Ag2SO4 | 0.573 | 0.796 | 0.979 | 1.15 | 1.3 | 1.46 |
| Sodium acetate trihydrate | NaCH3COO·3H2O | 36.3 | 46.42 | 65.4 | 138 (58 °C) | – | – |
| Sodium bromide | NaBr | – | – | – | 118 | 118.3 | 121.2 |
| Sodium carbonate decahydrate | Na2CO3·10H2O | 6.86 | 21.66 | – | – | – | – |
| Sodium carbonate monohydrate | Na2CO3·H2O | – | – | 48.9 | 46.2 | 44.5 | 44.5 |
| Sodium carbonate anhydrous | Na2CO3 | 7.1 | 21.4 | 48.5 | 46.5 | 45.8 | 45.5 |
| Sodium chlorate | NaClO3 | 80.5 | 98.82 | 115.2 | -138 | -167 | 204 |
| Sodium chloride | NaCl | 35.6 | 35.8 | 36.42 | 37.05 | 38.05 | 39.2 |
| Sodium dichromate dihydrate | Na2Cr2O7·2H2O | 163.2 | 180.16 | 220.5 | 283 | 385 | – |
| Sodium dihydrogen phosphate dihydrate | NaH2PO4·2H2O | 57.7 | 85.2 | 138.2 | – | – | – |
| Sodium dihydrogen phosphate anhydrous | NaH2PO4 | – | – | – | 179.3 | 207.3 | 284.4 |
| tetra-Sodium diphosphate decahydrate | Na4P2O7·10H2O | 2.7 | 5.48 | 12.5 | 21.9 | 30 | 40.26 |
| Sodium disulfite | Na2S2O5 | – | 65.3 | 71.1 | 79.9 | 88.7 | -100 |
| Sodium fluoride | NaF | -3.6 | 4.1 | – | – | – | – |
| Sodium hydrogen carbonate | NaHCO3 | 6.89 | 9.6 | 12.7 | 16 | 19.7 | 23.6 |
| di-Sodium hydrogen phosphate dodecahydrate | Na2HPO4·12H2O | 1.63 | 7.7 | – | – | – | – |
| di-Sodium hydrogen phosphate heptahydrate | Na2HPO4·7H2O | – | – | 55 | – | – | – |
| di-Sodium hydrogen phosphate dihydrate | Na2HPO4·2H2O | – | – | – | 83 | 92.4 | – |
| di-Sodium hydrogen phosphate anhydrous | Na2HPO4 | – | – | – | – | – | 104.1 |
| Sodium hydroxide monohydrate | NaOH·H2O | – | 109.22 | 126 | 178 | – | – |
| Sodium hydroxide | NaOH | – | – | – | – | 313.7 | 341 |
| Sodium iodate | NalO3 | – | – | – | – | 27 | 32.8 |
| Sodium iodide | Nal | – | – | – | – | 295 | 303 |
| Sodium nitrate | NaNO3 | 70.7 | 88.3 | 104.9 | 124.7 | 148 | 176 |
| Sodium nitrite | NaNO2 | 73 | 84.52 | 95.7 | 112.3 | 135.5 | 163 |
| Sodium perchlorate monohydrate | NaClO4·H2O | 167 | 181 | 243 | – | – | – |
| tri-Sodium phosphate dodecahydrate | Na3PO4·12H2O | 1.5 | 12.11 | 31 | 55 | 81 | 108 |
| Sodium sulfate decahydrate | Na2SO4·10H2O | 4.56 | 19.19 | – | – | – | – |
| Sodium sulfate anhydrous | Na2SO4 | – | – | 48.1 | 45.26 | 43.09 | 42.3 |
| Sodium sulfite | Na2SO3 | – | – | 37 | 33.2 | 29 | 26.6 |
| di-Sodium tetraborate | Na2B4O7 | 1.2 | 2.7 | 6 | 20.3 | 31.5 | 52.5 |
| Sodium thiosulfate pentahydrate | Na2S2O3·5H2O | 52.5 | 70.07 | 102.6 | – | – | – |
| Sodium thiosulfate anhydrous | Na2S2O3 | – | – | – | – | 245 | 266 |
| Strontium chloride hexahydrate | SrCl2·6H2O | 44.1 | 53.85 | 66.6 | 85.2 | – | – |
| Strontium hydroxide octahydrate | Sr(OH)2·8H2O | 0.35 | 0.7 | 1.5 | 3.13 | 7.02 | 24.2 |
| Strontium nitrate | Sr(NO3)2 | – | – | 91.2 | 94.2 | 97.2 | 101.2 |
| Zinc chloride | ZnCl2 | – | – | 453 | 488 | 541 | 614 |
| Zinc nitrate tetrahydrate | Zn(NO3)2·4H2O | – | – | 211.5 | – | – | – |
| Zinc sulfate heptahydrate | ZnSO4·7H2O | 41.6 | 53.8 | – | – | – | – |
| Zinc sulfate monohydrate | ZnSO4·H2O | – | – | – | 76.5 | 66.7 | 60.5 |
Some key points regarding the solubility of inorganic compounds in water:
Ionic compounds
- Ionic compounds, such as salts, are generally soluble in water due to the strong interactions between the ions and water molecules.
- The solubility of ionic compounds depends on the strength of the ionic bonds and the hydration energy of the individual ions.
- Highly soluble ionic compounds include sodium chloride (NaCl), potassium nitrate (KNO3), and calcium chloride (CaCl2).
Covalent compounds
- Covalent inorganic compounds can have varying degrees of solubility in water, depending on their polarity and the strength of the intermolecular interactions with water.
- Polar covalent compounds, such as ammonia (NH3) and hydrogen peroxide (H2O2), are generally soluble in water.
- Non-polar covalent compounds, such as carbon dioxide (CO2) and methane (CH4), have limited solubility in water.
Solubility rules
There are several general rules that can be used to predict the solubility of inorganic compounds in water:
- Salts of alkali metals (e.g., sodium, potassium) and ammonium are generally soluble.
- Salts of alkaline earth metals (e.g., calcium, barium) are generally insoluble, except for their nitrates, acetates, and chlorides.
- Halides (e.g., chlorides, bromides, iodides) are generally soluble, except for silver halides and lead(II) halides.
- Sulfates are generally soluble, except for those of barium, calcium, and lead.
