Question

Raoult's Law states that the partial vapor pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture.

As we know that the liquid and vapour in a container are at dynamic equilibrium,

So the mole fraction which is mentioned in Raoult's Law is measured at equilibrium or initially?

Answer 1

The mole fraction in Raoult's Law refers to the equilibrium mole fraction when calculating partial vapor pressures, ensuring an accurate determination of vapor pressure for each component in a mixture at dynamic equilibrium.

Step-by-step explanation:

The mole fraction mentioned in Raoult's Law refers to the mole fraction at the state of dynamic equilibrium between the liquid and vapor phases in the container.

This means that the vapor pressures calculated using Raoult's Law are influenced by the concentrations of the components when the system has reached equilibrium.

In other words, the partial vapor pressure of a component (PA) is the product of the mole fraction of that component in the equilibrium state (XA) and the vapor pressure of the pure component (P0A).

When dealing with volatile solutes, Raoult's Law can still be applied to calculate the partial vapor pressure of each component individually. For a solution with two volatile components, A and B, the total vapor pressure of the solution (Ptot) is simply the sum of the individual vapor pressures.

In the practice of distillation, Raoult's Law outlines how the more volatile substance can be separated from its less volatile counterpart due to the differences in vapor pressures and mole fractions in the vapor phase compared to the liquid phase.