There are several rules of solubility. Here we will discuss some basic rules.
1) Dilute solution:
If the solution has a lesser amount of solute than the highest amount then it is capable to dissolve (its solubility), it is a dilute solution.
2) Saturated solution:
If the amount of solute is accurately the same amount as its solubility, it is saturated solution. A saturated solution is that in which the highest amount of solute has been dissolved. The reverse is a dilute solution; these solutions can soluble more solute.
3) Concentrated solution:
If there is more solute than the highest amount then it is able to be dissolved, the overload solute separates from the solution. If this separation procedure includes crystallization, it makes a precipitate. Precipitations decrease the concentration of the solute to the saturation in sort to raise the stability of the solution.
Pressure and temperature also change solubility. A compound which is soluble in water forms an aqueous solution.
There are some solubility rules for common ionic solids.
- Salts having Group I elements (Li+, Na+, K+, Cs+, Rb+) are soluble . There are only some exceptions to this rule. Salts which have the ammonium ion (NH4+) are also soluble.
- Salts containing nitrate ion (NO3-) are usually soluble.
- Salts consisting Cl -, Br -, or I – are usually soluble. Main exceptions to this rule are Halide salts of Ag+, Pb2+, and (Hg2)2+. Consequently, AgCl, PbBr2, and Hg2Cl2 are insoluble.
- The majority of silver salts are impossible to solve. AgNO3 and Ag (C2H3O2) are generally soluble salts of silver; virtually all others are insoluble.
- Mainly sulfate salts are soluble. Essential exceptions to this rule involve CaSO4, BaSO4, PbSO4, Ag2SO4 and SrSO4.
- The majority hydroxide salts are only faintly soluble. Salts of Hydroxide Group I elements are soluble. Hydroxide salts of Group II elements (Ca, Sr, and Ba) are faintly soluble. Hydroxide salts of transition metals and Al3+ are unsolvable. Thus, Fe(OH)3, Al(OH)3, Co(OH)2 are not soluble.
- Mainly sulfides of transition metals are highly insoluble, as well as CdS, FeS, ZnS, and Ag2S. Arsenic, antimony, bismuth, and lead sulfides are also insoluble.
- Carbonates are commonly insoluble. Group II carbonates (CaCO3, SrCO3, and BaCO3) are insoluble, as are FeCO3 and PbCO3.
- Chromates are normally insoluble. Examples include PbCrO4 and BaCrO4.
- Phosphates such as Ca3(PO4)2 and Ag3PO4 are commonly insoluble.
- Fluorides such as BaF2, MgF2, and PbF2 are commonly insoluble.