Intermolecular forces solutions

To have an ideal solution, the solvent-solvent, solute-solute and solvent-solute intermolecular forces should be as nearly identical as possible. Solution (c) consisting of CH4( ) dissolved in CH3CH3( ) would be the most ideal. 

SOL.24.1. Prigogine, Forces intermoleculaires et volume d exces des solutions (Intermolecular forces and excess volume in solutions), Bull. Soc. Chim. Beiges 62, 125-137 (1953). 

The dissolution of a solute in a solvent has associated with it a free-energy change, AG = AH — TAS. The enthalpy change is the heat of solution (AHsoin), and the entropy change is the entropy of solution (ASsoin). Heats of solution can be either positive or negative, depending on the relative strengths of solvent-solvent, solute-solute, and solvent-solute intermolecular forces. Entropies of solution are usually positive because disorder increases when a pure solute dissolves in a pure solvent. 

In an ideal solution intermolecular forces are the same between all molecules, regardless of species differences in those forces produce nonzero values for excess properties. In particular, magnitudes and signs of excess properties are determined by imbalances in the strengths of interactions between molecules of the same component (like interactions) as compared to those between molecules of different components (unlike interactions). Figure 5.1 illustrates these points by showing at 25°C for... 

Types of Solutions Intermolecular Forces and Solubility IntermoleciJar Forces h Solution Liquid Solutions... 

In solutions intermolecular forces between the dissolved substance and the solvent may affect the volume of the solution. This molecular effect can e.g. be seen when concentrated saline solutions are made the volume of the mix will normally be considerably less than the sum of the component volumes. 

The enthalpic term is negative when there are attractive interactions between the components, a condition that decreases AGm and favors miscibility. For an ideal solution, intermolecular forces between like and unlike molecules (i.e., the two components) are similar and AHm = 0. 

---