Vapour Pressure Formula
Question 1: What is Raoult’s law and its application?
Answer:
Raoult’s law states that the partial pressure of a pure component (liquid or solid) in a perfect mixture of liquids is equal to the vapour pressure of that component multiplied by the mole fraction in the mixture.
Raoult’s law is applicable:
- To evaluate the reduction in non-volatile solute vapour pressure.
- To evaluate the liquids’ ability to bind strongly.
Question 2: Write the Vapour Pressure formula.
Answer:
A solution is created when a solid is dissolved in a liquid. The resultant vapour pressure of this solution is decreased when the solute is introduced. Raoult’s law, which describes how the vapour pressure of a liquid changes when a solute is added, is used to calculate vapour pressure.
Psolution = (Xsolvent)×(P° solvent)
where,
Psolution is the vapour pressure of a solution
Xsolvent is the mole fraction of solvent in a solution
P° solvent is the vapour pressure of a solvent
Question 3: For what type of solutions, Raoult’s law is valid?
Answer:
Raoult’s law is only valid for ideal solutions. The solvent-solute interaction is the same as a solvent-solvent or solute-solute interaction in an ideal solution. This suggests that both the solvent and the solute expend the same amount of energy to reach the vapour phase as they do in their pure states.
Question 4: Write the limitations of Raoult’s law.
Answer:
There are limitations of Raoult’s law that are mentioned below:
Since Raoult’s law applies to ideal solutions, i.e., those in which the gas phase exhibits thermodynamic features resembling a combination of ideal gases, it is particularly pertinent. The fact that they are uncommon and hard to find is the only negative. Because distinct attractive forces exist in many liquid mixes, certain solutions depart from Raoult’s equation.
Vapour Pressure
Vapour pressure is the force exerted by a liquid’s (or solid’s) vapour above the surface of the liquid. At a particular temperature and thermodynamic equilibrium, this pressure is formed in a closed container. The rate of liquid evaporation is controlled by the equilibrium vapour pressure. The vapour pressure increases with increasing temperature. When atmospheric pressure and vapour pressure are equal, a liquid is said to have reached its boiling point.