There are a lot of factors that affect the solubility of a substance in another. Some of them are: temperature, polarity, pressure, and molecular size.
- Forces between particles
The nature of intermolecular forces in both the solute and the solvent determines the rate of solubility between them. When a substance dissolves in another, it must overcome the attractive forces between two of them. The dissolving solute ought to be able to break up the aggregation of molecules in the solvent. This means overcoming the hydrogen bonds between the molecules or the dispersion forces between molecules in a non-polar solvent. The molecules of the solvent must therefore have enough attraction for the particles of the solute to take them away one after another from their neighbors in the undissolved solute. If the solute is ionic, only an extremely polar solvent such as water provides enough interaction to result to dissolution. If the solute particles are polar molecules, they are easily dissolved in polar solvents like alcohols. Non polar solute on the other hand dissolves in non-polar solvents. The reason is not because polar solvent molecules cannot conquer the weak dispersion forces between the solute molecules, but due to the fact that these dispersion forces are extra ordinarily weak to overcome the dipole-dipole interaction that exists between the solvent molecules.
Generally, like dissolves like. Ionic and polar compounds are soluble in polar solvents like water or liquid ammonia. Nonpolar compounds are soluble in non-polar solvents, like carbon tetrachloride, and hydrocarbon solvents like gasoline.
The solubility of gases in water depends very much how polar the gas molecules are. Those gases whose molecules are polar are much more soluble in water than non-polar gases. Ammonia, a highly polar molecule, is extremely soluble in water (89.9 g/100 g H2O) and hydrogen chloride (82.3 g/100 g H2O). Helium and nitrogen are nonpolar molecules. Helium is mere partially soluble (1.8 X 10-4 g/100 g H2O), like in nitrogen (2.9 X 10-3 g/100 g H2O)
Solubility and inter-particle bonds in various types of compounds and their relative solubilities in water, a polar solvent; in alcohol, a less polar solvent; and in benzene, a non-polar solvent
The solubility of substances varies at different temperature. Usually, the solubility of solids and liquids rises at higher temperature but the solubility of gases diminishes with an increase in temperature. This property of gases causes is a great concern for the life of fishes in lakes, oceans, and rivers. Fish needs dissolved oxygen to stay alive. If the temperature of their water habitat increases, the concentration of dissolved oxygen is reduced and the life of the fishes is at stake.
The pressure on the surface of a solution has less effect on the solubility of solids and liquids but a great effect on the solubility of gases.