To understand the polarity of glycerol and fatty acid chains, we first need to examine their molecular structures. Glycerol, a three-carbon alcohol with hydroxyl (–OH) groups, is indeed polar. The presence of these hydroxyl groups allows glycerol to form hydrogen bonds with water, making it soluble in water.
On the other hand, fatty acid chains are primarily long hydrocarbon chains, which are nonpolar due to the absence of significant electronegative atoms. The long carbon-hydrogen bonds do not interact well with polar solvents like water, making fatty acids hydrophobic.
When glycerol combines with three fatty acid chains to form a triglyceride, the overall molecule’s polarity changes. The triglyceride is largely nonpolar because the three fatty acid chains dominate the structure, contributing to a hydrophobic character. Although the glycerol part retains its polar characteristics, it is covered and surrounded by the long nonpolar fatty acid chains in the triglyceride molecule. As a result, triglycerides are considered nonpolar and are insoluble in water.
In summary, while glycerol itself is polar and fatty acid chains are nonpolar, the formation of triglycerides results in a predominantly nonpolar molecule.