CBSE Class 12-science Answered

Hi,

Raoult's law states that for a solution of volatile liquids, the partial vapour pressure of each component in the solution is directly proportional to its mole fraction. Thus if there is a solution of two liquid components I and II, then,

for component I,
p ₁ ∝ x₁ 
 
For component II,
 
where
p₁ , p₂ = Partial vapour pressure of two volatile components I and II of the solution
= Vapour pressure of pure components I and II
x₁ , x₂ = Mole fractions of the components I and II
According to Dalton's Law of partial pressure:
p_total  = p₁ + p₂ 
        = p₁ °x₁ + p ₂ °x₂ ​
​        = (1-x₂)p₁ ° + p ₂ °x₂ ​
p_{total =} p₁ ° + ( p ₂ °-p₁ °) x₂ ​