Factors Affecting Solubility

Pollution of air and water of Class 8

Factors Affecting Solubility

NATURE OF SOLUTE:

Ionic compounds or polar compounds are more soluble in polar solvents like water. Non-polar compounds are more soluble in non-polar solvents like benzene.

NATURE OF SOLVENT:

The solvents which have high dielectric constants can dissolve polar and ionic compounds to a greater extent than the solvents with low dielectric constants

e.g.NaCl is highly soluble in water. NaCl is sparingly soluble in benzene.

TEMPERATURE:

For most of the substances, solubility increases with the increase in temperature.

RATE OF DISSOLUTION:

Though each solute has a certain fixed value of solubility, the rate at which a solute dissolves in a particular solvent depends on certain factors.

Size of the solute particles:The smaller the solute particles, the faster are the rate of dissolution. This is because division into smaller particles increases the surface area of contact between the solute and solvent particles. Greater area of contact increases the rate of dissolution.
Agitation of solution:Agitation or stirring improves the contact between the solute and solvent molecules. Consequently, the rate of dissolution increase.
Temperature:Rate of dissolution of most of the solids increases with the increase in temperature because the solubility of the solid increases with the increase in temperature. However, in case of some solids the rate of dissolution increases with the increase in temperature upto a certain point and decreases beyond a certain point.

e.g. Na₂SO₄. 10H₂O and Ca SO₄

The solubility of gases in liquids shows a different trend with regard to the effect of temperature. In these solutions, the solubility is also influenced by the pressure.

TEMPERATURE:

With the increase in temperature, the solubility of a gas in a particular liquid decreases.

PRESSURE:

The effect of pressure on the solubility of a gas in a liquid is given by Henry’s law, which states that at constant temperature the increase in pressure on the surface of the liquid increases the solubility of gas in liquid.