Why fats are poorly soluble in water. What part of the molecule, when dissolved, faces the surface of the water, and which inside of the “oily drop”?

Long acid radicals are non-polar and have hydrophobic properties. It is they who determine many properties of fats, in particular their insolubility in water. The carboxyl group of the acid is polar; therefore, it has hydrophilic properties. But it is very small in comparison with the radical. In an aqueous solution, the hydrophilic parts face the surface of the water, and the hydrophobic tails protrude above the surface.

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