Relative Lowering of Vapour Pressure: The relative lowering of vapour pressure is a measure of the amount of solute present in a solution, compared to the amount of solvent in the same solution. It is defined as the ratio of the difference in the vapour pressures of the pure solvent and the solution to the vapour pressure of the pure solvent. Mathematically, it can be expressed as:

(P₀ – Ps) / P₀

Where,

• P₀ is the vapour pressure of the pure solvent
• P_s is the vapour pressure of the solution
• The difference (P₀ – P_s) is the lowering of the vapour pressure due to the presence of solute.

Relative Lowering of Vapour Pressure

The relative lowering of vapour pressure is a colligative property, which means it depends only on the number of solute particles in the solution and not on the identity of the solute particles. Therefore, it is a useful tool for determining the molecular weight of an unknown solute.

The relative lowering of vapour pressure is also related to other colligative properties, such as boiling point elevation, freezing point depression, and osmotic pressure. All of these properties depend on the number of solute particles present in the solution, and not on the identity of the solute particles.

The relative lowering of vapour pressure is commonly used in many industries, including pharmaceuticals, food and beverage, and chemical manufacturing, to determine the concentration of solutes in a solution.

Follow on Facebook

By Team Learning Mantras