SOLUBILITY OF COMPLETELY SOLUBLE SALTS

Completely soluble salts are those that dissolve entirely in water to form a homogeneous solution. The solubility of these salts in water depends on various factors such as temperature, pressure, and the nature of the salt and solvent.

There are some general rules for predicting the solubility of ionic compounds in water. These rules are based on the principle that “like dissolves like,” where polar substances dissolve in polar solvents, and nonpolar substances dissolve in nonpolar solvents.

1. Salts containing group 1 cations (Li+, Na+, K+, Rb+, and Cs+) are completely soluble in water.

2. Salts containing the ammonium ion (NH4+) are completely soluble in water.

3. Salts containing the nitrate ion (NO3-) are completely soluble in water.

4. Salts containing the chloride ion (Cl-) are mostly soluble in water. However, some chloride salts of less electronegative metals such as AgCl and PbCl2 are insoluble.

5. Salts containing the sulfate ion (SO42-) are mostly soluble in water. However, some sulfate salts of less electronegative metals such as BaSO4 and PbSO4 are insoluble.

6. Salts containing the carbonate ion (CO32-) and the phosphate ion (PO43-) are mostly insoluble in water. However, some of their soluble salts, such as Na2CO3 and Na3PO4, are completely soluble.

These rules are useful in predicting the solubility of completely soluble salts in water and can help in identifying insoluble salts. Keep in mind that these rules are not absolute, and some exceptions to them can occur.