Which of the following compounds is hydrophobic and likely to be insoluble in water?

• A. ${\mathrm{Na}}^{\mathrm{+}} {\mathrm{Cl}}^{\mathrm{-}}$ (Sodium chloride)
• B. $C_2{H}_5\mathrm{OH}$ (Ethanol)
• C. ${\mathrm{CH}}_3\mathrm{COOH}$ (Acetic acid)
• D. $C_6{H}_{14}$ (Hexane)

Answer: (D)

Verified step by step guidance

1. Understand the concept of hydrophobicity: Hydrophobic compounds are those that repel water and do not dissolve in it. They are typically nonpolar, lacking the ability to form hydrogen bonds with water.
2. Identify the nature of each compound: Sodium chloride is ionic, ethanol and acetic acid are polar due to their ability to form hydrogen bonds, while hexane is nonpolar.
3. Examine the structure of hexane: Hexane is a hydrocarbon with the formula C₆H₁₄. It consists of a chain of carbon atoms bonded to hydrogen atoms, making it nonpolar.
4. Consider solubility principles: Nonpolar compounds like hexane are insoluble in polar solvents like water because they cannot form favorable interactions with water molecules.
5. Conclude based on properties: Given hexane's nonpolar nature, it is hydrophobic and likely to be insoluble in water, unlike the other compounds listed.