Question

Consider a binary mixture of volatile liquids.
For which of the following graph, solvent-solute interaction is equal to that of solvent-solvent and the solute-solute interactions?

Answer 1

Ideal solutions:
These solutions obey Raoult's law.
Here, the solvent-solute interaction are equal to that of solvent-solvent and the solute-solute interactions.
Option (a) :


Here,
$\text{Total pressure}=P_A+P_B$
Option (b) shows positive deviaition from Raoult's law. Here ,
$P_T>p_A^{\circ }{\chi }_A+p_B^{\circ }{\chi }_B$

Option (c) shows negative deviation from Raoult's law:
Here,
$P_T<p_A^{\circ }{\chi }_A+p_B^{\circ }{\chi }_B$