Question

State Raoult's law for the solution containing volatile components. What is the similarity between Raoult's law and Henry's law?

Answer 1

Raoult's law:- It 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. Mathematically, Raoult's law for the solution containing volatile components is:

For component 1,

$p_1\propto x_1$

$p_1=p_1^{\circ }{x}_1$ ---- (1)

$p_1=$ Vapour pressure of component 1 in solution.

$p_1^{\circ }=$ Vapour pressure of pure liquid component 1 at the same temperature

$x_1=$ Mole fraction of component 1 in solution.

Similarly for component 2 :

$p_2=p_2^{\circ }{x}_2$ ------ (2)

Raoult's law is a special case of Henry's law. The similarity between Raoult's law and Henry's law is that both laws state that the partial pressure of the volatile component is directly proportional to its mole fraction in the solution. In the case of Raoult's law, it is a liquid and in the case of Henry's law, it is a gas.