Understanding "Like Dissolves Like"

The principle of "like dissolves like" is key here. It means substances with similar polarities (how evenly electrons are distributed) tend to dissolve in each other.

* Nonpolar: Hexane and benzene are both nonpolar molecules. This means their electron distribution is fairly even, and they don't have significant positive or negative ends.

* Polar: Sodium chloride (NaCl) is an ionic compound. It's made up of positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-), creating a strong polar interaction.

Why hexane dissolves benzene:

* Similar polarities: Both hexane and benzene are nonpolar. They can interact through weak van der Waals forces (temporary, induced dipoles), which are enough to overcome the attractive forces holding the molecules together. This allows them to mix and dissolve.

Why hexane doesn't dissolve sodium chloride:

* Different polarities: Hexane (nonpolar) and sodium chloride (ionic, strongly polar) have very different polarities. The weak van der Waals forces in hexane are insufficient to overcome the strong electrostatic attractions between the Na+ and Cl- ions in sodium chloride.

In Summary:

* Hexane and benzene: Both nonpolar, weak interactions allow mixing.

* Hexane and sodium chloride: One is nonpolar, the other is strongly polar; their differences in polarity prevent them from dissolving in each other.