Question

Just because you mix two things together does not necessarily mean that they will form a homogeneous mixture (a solution).
For example, if you add sodium chloride, $NaCl$, to a container that has both hexane and water, the $NaCl$ will dissolve into the water, but will not be found in the hexane $C_6{H}_{14}$.
Which of the following statements BEST explains these observations?

• A. Polar water molecules form ion-dipole forces with the ions of $NaCl$. Hexane, being nonpolar, cannot form these ion-dipole interactions.
• B. Nonpolar hexane molecules tend to repel the ions that make up $NaCl$.
• C. Nonpolar hexane is less dense that water, so when the two are in the same container, any $NaCl$ that is added to the mixture sinks to the bottom of the container and cannot get into the hexane layer.
• D. Nonpolar hexane molecules and water molecules repel one another.

Answer 1

The correct option is A Polar water molecules form ion-dipole forces with the ions of $NaCl$. Hexane, being nonpolar, cannot form these ion-dipole interactions.

NaCl is ionic in nature and soluble in polar solvent and insoluble in non-polar solvent like hexane because polar water molecules form ion-dipole forces with the ions of NaCl, which is not sceen in case of hexane.