Question

Many people do not realize that animal fat is used to make most soap, which is interesting because we use soap to remove animal fat from our hands and clothing. Soap is made by subjecting animal lard to saponification, in which heat and a strong alkali (NaOH or KOH) release fatty acids in the form of sodium or potassium salts from triacylglycerols.

When mixed with water, the fatty acids in soap function as amphipathic molecules forming what?

Answer 1

When mixed with water, fatty acids in soap form amphipathic molecules that create micelles, which help trap and wash away dirt and grease.

Step-by-step explanation:

When animal lard is subjected to saponification using heat and a strong alkali such as sodium hydroxide (NaOH) or potassium hydroxide (KOH), the fatty acids are released in the form of their sodium or potassium salts. These salts are essentially soap molecules. When mixed with water, the fatty acid salts in the soap function as amphipathic molecules. An amphipathic molecule has both a hydrophobic (water-repelling) and a hydrophilic (water-attracting) part.

In the case of soap, the hydrocarbon chain is hydrophobic, while the ionic carboxylate group is hydrophilic. When soap molecules mix with water, they self-assemble into micelles, with the hydrophobic tails tucked away from the water and the hydrophilic heads facing outwards into the water, forming a spherical structure. These micelles trap dirt and grease within their center, allowing them to be washed away with water.