Answer to Question #317453 in General Chemistry for kimmay

Question

Which oil is more unsaturated and has the higher melting point, safflower oil or olive oil? Explain.

Answer 1

The melting point (and other properties) of an oil depends on its fatty acid content. More the unsaturated acids, the lower is the melting point of the oil. (Unsaturated fatty acids contain double bonds. Unsaturated cis fatty acid chains have lower melting points due to the kinks in the molecules. Unsaturated fatty acids with longer chain lengths have higher melting points, and are thus less fluid than unsaturated fatty acids with short-chain lengths.). Safflower oil has monounsaturated acids (10–21%) and even more percentage of polyunsaturated fatty acids (72–84%) compared to those in olive oil, which has monounsaturated acids (55–83%) and only 3.5–22.5% polyunsaturated acids. Since safflower oil has far more amounts of polyunsaturated acids, its m.p. is lower than that of olive oil.