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Solubility Rules for Inorganic Compounds

General Solubility of Inorganic Salts and Compounds


Know the solubility rules for inorganic salts.

These are aqueous solutions of inorganic compounds. It's helpful to know the solubility rules so that you can predict which compounds will form solutions.

Ben Mills
These are the general solubility rules for inorganic compounds, primarily inorganic salts. Use the solubility rules to determine whether a compound will dissolve or precipitate.

Generally Soluble Inorganic Compounds

Ammonium (NH4+),potassium (K+), sodium (Na+) : All ammonium, potassium and sodium salts are soluble. Exceptions: some transition metal compounds.

Bromides (Br), chlorides (Cl) and iodides (I): Most bromides are soluble. Exceptions: salts containing silver, lead, and mercury.

Acetates (C2H3O2): All acetates are soluble. Exception: silver acetate is only moderately soluble.

Nitrates (NO3): All nitrates are soluble.

Sulfates (SO42–): All sulfates are soluble except barium and lead. Silver, mercury(I), and calcium sulfates are slightly soluble. Hydrogen sulfates (HSO4) (the bisulfates) are more soluble than the other sulfates.


Generally Insoluble Inorganic Compounds

Carbonates (CO32–), chromates (CrO42–), phosphates (PO43–), silicates (SiO42–): All carbonates, chromates, phosphates and silicates are insoluble. Exceptions: those of ammonium, potassium and sodium. An exception to the exceptions is MgCrO4, which is soluble.

Hydroxides (OH): All hydroxides (except ammonium, lithium, sodium, potassium, cesium, rubidium) are insoluble. Ba(OH)2, Ca(OH)2 and Sr(OH)2 are slightly soluble.

Silver (Ag+): All silver salts are insoluble. Exceptions: AgNO3 and AgClO4. AgC2H3O2 and Ag2SO4 are moderately soluble.

Sulfides (S2): All sulfides (except sodium, potassium, ammonium, magnesium, calcium and barium) are insoluble.

Aluminum sulfides and chromium sulfides are hydrolyzed and precipitate as hydroxides.

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