Lipids are soluble in which type of solvents?

• A. Organic solvents
• B. Water
• C. Gases
• D. Vacuum

Answer: (A)

Lipids are largely nonpolar molecules with long hydrocarbon chains, so they dissolve best in nonpolar organic solvents. This follows the principle that like dissolves like—nonpolar substances mix with nonpolar solvents because they interact through weak dispersion forces. Water is polar and forms strong hydrogen bonds, which makes it unfavorable for nonpolar lipids to dissolve, so lipids are mostly insoluble in water. A gas or vacuum isn’t a solvent in the same sense as a liquid organic solvent, so they don’t dissolve lipids. Consequently, lipids are soluble in organic solvents such as hexane or chloroform, which are nonpolar and compatible with lipid structure.