I ask because to make an ideal solution the intermolecular forces between the molecules of solvent and solute respectively should be similar and after mixing they should also be similar to what they were before mixing. But if we mix solid solute in liquid solvent then individually their respective intermolecular forces will be different from each other, because one component is solid and the other is liquid, hence the intermolecular forces in the solid component should be greater than the intermolecular forces in the liquid component.
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4$\begingroup$ Ideal solutions do not exist, like ideal gases do not exist Both are simplified models of reality. $\endgroup$– PoutnikCommented Jul 30, 2023 at 4:43
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1$\begingroup$ Also in chemistry you must think of the precision a model predicts for some behavior. Any model good to 4 significant figures would be considered perfect by a chemist. So chemistry isn't like pure math where $\pi$ has been calculated to over a hundred trillion digits. $\endgroup$– MaxWCommented Jul 30, 2023 at 6:00
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Once the solid dissolves in the liquid it is present only as molecules, for example solid naphthalene completely dissolving in benzene. The intermolecular forces between the molecules are then of three types solvent-solvent, solute-solute and solvent-solute, how big each is depends on the types of molecules and how important each is to the total energy/entropy of mixing depends on their relative concentrations, usually converted into mole fractions.
You mention an ideal solution. In thermodynamics an ideal gas or ideal solution is one that follows a defined standard behaviour. The ideal gas is one that obeys the perfect gas law, and this is found to be the case for many gasses but only, for example, at v. low pressure. The ideal solution is one that also follows some standard behaviour but the model of ideality depends on the type of system, divided between non-electrolytes and electrolytes. For non-electrolytes the ideal solution is defined as one whose parameters for the free energy of mixing follow that for an ideal gas, i.e. $\displaystyle \Delta G_{mix}=RT \sum_i x_i\ln(x_i)$ where $x_i$ is the mole fraction of species $i$ and that $\Delta H_{mix} =0$. The entropy of mixing is therefore $\Delta S_{mix}=-\left( \partial \Delta G_{mix}/\partial T\right)_P=-R \sum_i x_i\ln(x_i)$.
