What makes triglycerides insoluble in water?

• A. Water's polarity
• B. Hydrophobic tails
• C. Presence of phosphate groups
• D. Ionic bonds

Answer: (B)

Water can form strong hydrogen bonds with other polar or charged parts of molecules. Triglycerides, however, have three fatty acid tails that are long chains of mostly carbon and hydrogen, which are nonpolar. That nonpolarity means these tails don’t engage well with water, so they are hydrophobic. Water prefers to interact with itself rather than with nonpolar groups, causing triglycerides to separate from the aqueous phase rather than dissolve. Since there aren’t polar or ionic groups like phosphates or charges to create favorable water interactions, the overall molecule remains insoluble in water.