Question

This is for an Ochem Lab, in which soap was produced.

Explain in your own words how soap "cleans". Given that bacteria clings to our skin via the oils on our skin, do you think regular soap is able to get rid of bacteria?

Answer 1

Soaps are molecules of sodium or potassium salts of long chain fatty acid of which the fatty acid chain is hydrophobic in nature.This is the non-polar hydrocarbon chain or tail that does not interact or cling with water molecules but with oils on the skin.However ,the ionic polar head of the fatty acid chain with end group -COO^- Na⁺ interact with water molecules via electrostatic attractions.This end of the soap molecule is called the hydrophillic head.

Hydrophobic end of soap molecule or tail escapes water to dig deep into oils clinging to our skin,while the hydrophillic head keeps hanging out of the oil.Also the hydrocarbon tail cluster around oils as they interact with each other by dispersion forces forming structures called micelles.These miscelles repel each other and thus get dispersed in water forming an emulsion.The hydrophobic tail breaks the oils molecules which thus gets washed away on rinsing,

Any bacteria attached to the oils also gets washed away along with the oil.So a regular soap even works in removing bacteria from our skin