Why does "like dissolves like"?

It is generally believed that "like dissolves like". It means polar solute dissolve in polar solvent, while non-polar solute tend to dissolve in non-polar solvent. According to the van der Waals force, does permanent dipole-induced dipole forces larger than London dispersion force?

From thermodynamics, G=H-TS, not only the enthalpy but the entropy changes the Gibbs free energy. For polar system, positive and negative charges attract on another. However, in non-polar system, weak attractions between solute and solvent molecules make the entropy dominant.

What happens when non-polar and polar molecules are added together? Polar molecules tend to bind each other and push non-polar molecules out of the way.

影響溶解度的原理：
1. 分子間的吸引力
2. 系統的亂度


ref:
http://www.scribd.com/doc/6402856/24-CHEMISTRY-LESSONS
http://www.chalkbored.com/lessons/chemistry-12/study-note-2-20.pdf