Question

What are the factors on which the colligative properties of a solution depend?

Answer 1

Colligative properties of a solution:

• The property of a solution depends only on the concentration of ion/molecule/atom of the solute.
• The colligative properties are osmotic pressure, depression in freezing point, boiling point elevation, and relative lowering of vapor pressure.

The factors on which the colligative properties of a solution depend are discussed below:

Osmotic pressure:

• The process in which the movement of the solvent molecules through a semi-permeable membrane takes place from a pure solvent to a solution is known as osmosis.
• The flow of solvent can be controlled by applying pressure, this pressure is known as osmotic pressure.

Depression in freezing point:

• Freezing point depression has a direct relation with the molal concentration of the solute.
• Depression in freezing point is given as $∆{\mathrm{T}}_{\mathrm{f}}={\mathrm{K}}_{\mathrm{f}}.\mathrm{m}$ where ${\mathrm{K}}_{\mathrm{f}}$ is the freezing point depression constant.

Elevation in boiling point:

• Boiling point elevation has a direct relation with the molal concentration of the solute.
• It is given as $∆{\mathrm{T}}_{\mathrm{b}}={\mathrm{K}}_{\mathrm{b}}.\mathrm{m}$ where ${\mathrm{K}}_{\mathrm{b}}$ is the boiling point elevation constant.

Relative lowering of vapor pressure:

• Raoult’s law gives the relation between the vapor pressures and the concentration of the solution.
• It states that “In an ideal solution, the partial pressure exerted by any component is equal to the product of the vapor pressure of the pure component and its mole fraction in the solution values."
• It is given as ${\mathrm{p}}_1={\mathrm{x}}_1{{\mathrm{p}}_1}^0$, where ${{\mathrm{p}}_1}^0$is the vapor pressure of the pure solvent and ${\mathrm{x}}_1$ is the mole fraction of the solvent.