Hexane is a nonpolar substance, meaning it lacks a charge and does not have a significant difference in electronegativity between its atoms. On the other hand, saltwater, which is a solution of sodium chloride (NaCl) in water, is a polar substance due to the presence of ionic bonds between the sodium and chloride ions.
When we consider the solubility of hexane in saltwater, we need to understand the nature of solvents and solutes. Like dissolves like, so polar solvents tend to dissolve polar solutes, while nonpolar solvents dissolve nonpolar solutes.
In the case of hexane, being a nonpolar solvent, it has weak intermolecular forces such as London dispersion forces. These forces are relatively weak and arise from temporary fluctuations in electron distribution within molecules. Hexane is commonly used as a nonpolar solvent in various applications, such as extracting oils and fats.
Saltwater, on the other hand, consists of water molecules with polar covalent bonds and sodium chloride ions held together by ionic bonds. In this solution, the positive sodium ions (Na+) are attracted to the negative ends of water molecules (oxygen atoms), while the negative chloride ions (Cl-) are attracted to the positive ends of water molecules (hydrogen atoms). This attraction occurs through the formation of hydration shells around the ions.
Due to the strong ionic bonds between the sodium and chloride ions, salt (NaCl) dissolves readily in water. However, hexane being nonpolar, lacks the ability to form strong interactions with the polar water molecules. As a result, hexane is not soluble in water, including saltwater.
When we consider the solubility of hexane in saltwater specifically, it is important to note that the presence of salt does not change the nonpolar nature of hexane. The ionic bonds in saltwater do not provide a favorable environment for nonpolar solutes like hexane to dissolve.
Hexane is not soluble in saltwater. The polar nature of water and the ionic nature of the salt do not allow for effective interaction with the nonpolar hexane molecules. Hexane remains as a separate phase when mixed with saltwater, with the two substances not forming a homogeneous solution.
Personal Experience:
I have personally conducted experiments in the laboratory where I observed the lack of solubility of hexane in saltwater. When attempting to mix hexane and saltwater in a test tube, I noticed that the hexane formed a distinct layer on top of the saltwater. Despite vigorous shaking and stirring, the hexane did not dissolve or mix with the saltwater. This observation further supports the fact that hexane is not soluble in saltwater due to their differing polarities.