Colligative Properties

Colligative properties are “properties of a solution that depends on the ratio of solute particles to the number of solvent molecules in a solution and not on the detailed properties of molecules themselves”.

Colligative Properties

Colligative Properties

Colligative properties do not depend upon the nature of the solute.The four Colligative Properties are stated below:

  • Vapor pressure depression
  • Boiling point elevation
  • Melting point depression
  • Osmotic pressure.

Vapor Pressure Depression

It indicates liquid’s evaporation rate. “It is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system”. Pressure is a standard unit that is used to measure vapor pressure. The vapor pressure of a substance increases ( not continuously) with increase in temperature.

Boiling Point Elevation

“It is a phenomenon that the boiling point of a liquid will be higher when another compound is added, meaning that a solution has a higher boiling point than a pure solvent”. It is a phenomenon that occurs for all solutes in a all solution including ideal solutions.

Melting Point Depression

“ It is a phenomenon of reduction of the melting point of a material with reduction of its size”. Two techniques are used to measure the melting point of a nanoparticle. These nanoparticles can be melted through electron beam of the Transmission electron microscope. It restraint the pressure range where melting point depression can be tested.

Nowadays nano calorimeters are used to measure the melting temperature and enthalpy of nanoparticles.

Osmotic Pressure

“ It is the minimum pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane”.

Various applications of osmotic pressure are stated below:

  • It is one of the vital factor affecting the cells. Organisms uses mechanism called osmoregulation to reach balance in osmotic pressure. Isotonicity is a existence of a solution that produces no modification in the volume of the cell. Hypotonicity is a existence of a solution that source cells to swell. Hypertonicity is the presence of a solution that source cells to shrink.
  • Osmotic Pressure is necessary for filtering, that is generally used in water purification.

Practise This Question

Solute when dissolved in water: