How do intermolecular forces affect solvation?

1 Answer
Dec 10, 2015

On a molecular level, solvation involves the dispersion of solute molecules throughout a massive collection of solvent molecules in such a way that the solute particles cannot interact with each other.

This dispersion is more favorable when intermolecular forces are similar.

For example, in enough water, sodium chloride interacts with water via an ion-dipole interaction that turns out to be more favorable than the ion-pair interactions between sodium and chloride (normally ion-pair interactions tend to be stronger in general); the orientations are like so, since water has a partially positive side (the hydrogens) and a partially-negative side (the oxygen):

You might also see this kind of surrounded depiction called a hydration sphere.

By analogy, something like hexane can't dissolve in water, but something like ethanol can dissolve in water.

CHALLENGE: Why can ethanol dissolve in water? What intermolecular force do they share in common?