Formation of a binary solution from two liquid components can be considered as i) pure solvent $\rig

Question

Formation of a binary solution from two liquid components can be considered as i) pure solvent $\rightarrow$ separated solvent molecules, $\Delta H_{1}$ ii) pure solute $\rightarrow$ separated solute molecules, $\Delta H_{2}$. iii) separated solvent and solute molecules $\rightarrow$ solution, $\Delta H_{3}$. The solution so formed will be ideal if

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For ideal solutions there is no change in molecular interactions when the two components are mixed. In that case, there is no net enthalpy change of mixing. i.e., $\Delta_{mix } H=0$. The mixing process occurs in three steps (1) $A-A \rightarrow 2 A \quad \Delta H_{1}=+x$ (2) $B-B \rightarrow 2 B \quad \Delta H_{2}=+y$ (3) $2 A+2 B \rightarrow 2 A-B \quad \Delta H_{3}=-z$ From Hess's law, the enthalpy change of a onestep process is equal to the sum of the enthalpy changes of the multistep process. $\Delta_{soln } H=\Delta H_{1}+\Delta H_{2}+\Delta H_{3}=x+y-z=0$ because $x+y=z$