What needs to happen for a solute to dissolve in a particular solvent?

Answer: In order to a solute to dissolve in a solvent, both the attraction forces that bind the units of solute together and the intermolecular forces that bind the molecules of solvent together must be weaker than the attraction forces between the particles of solute and the molecules of solvent.

Explanation:

The solute particles in are binded together in virtue of attractive forces (the nature and strength of these forces depends on the particular solute).

The same happens with the solvent molecules: they are binded by attractive forces (similarly, the nature and strength of these forces depend on the particular solvent).

To get dissolved (form solution) the particles of solute must be separated and mixed with the solvent particles in a process called solvatation.

The solute particles must surrounded by the solvent particles.

When the forces of attraction between the solute particles and the solvent are stronger than the forces of attraction that bind the solute particles, the solute particles move away from the solid solute and are integrated into the solution.

The attractions between the solute and solvent molecules must be greater than the attractions keeping the solute together and the attractions keeping the solvent together.