What is soap?
'Soap' is defined as fat or oil combined with an alkali. The oil is derived from an animal or plant, whereas the alkali is a chemical known as lye. The lye used in the production of bar soap is sodium hydroxide. Potassium hydroxide is required for liquid soap.
Soap is produced by combining and then heating oil and lye. This chemical reaction is known as saponification. With soap bar production, the formula is then pressed into molds.
How Does Soap Work?
Soap can clean hands and dishes because of some pretty nifty chemistry. Soap molecules have on one end what's known as a polar salt, which is hydrophilic, or attracted to water. The other end of the molecule is a nonpolar chain of fatty acids or hydrocarbons, which is hydrophobic-meaning that it's repelled by water but attracted to grease and other oily substances. When you wash your hands, the soap forms something like a molecular bridge between the water and the dirty, germ-laden oils on your hands, attaching to both the oils and the water and lifting the grime off and away. Soaps can also link up with the fatty membranes on the outside of bacteria and certain viruses, lifting the infectious agents off and even breaking them apart. Once the oily dirt and germs are off your hands, the soap molecules thoroughly surround them and form tiny clusters, known as micelles, that keep them from attaching to anything else while they wash down the drain.
How does soap work to remove germs and pathogens during the handwashing process?
Soap and water do not kill germs; they work by mechanically removing them from your hands. Running water by itself does a decent job of pathogen removal, but soap allows you to tackle the hard-to-remove germs by acting like a crowbar. Soap molecules have two ends: hydrophilic, attracting water, and hydrophobic, repelling water.
First, the hydrophilic ends of the soap molecule attach to the water, and then the hydrophobic ends attach to the oils, pathogens, or other debris on the hand. After the soap has bonded with the germs on your hand the water can then wash it down the drain. This works because the soap molecule can attach to the germs more strongly than the germs can hold onto your skin.
Soap is powerful, but it cannot do all the work on its own. The amount of time you are rubbing your hands together and lathering up plays a massive role in handwashing efficacy. If you scrub your hands for just 15 seconds you remove about 90% of pathogens, but with an additional 15 seconds, you are removing 99.9% of pathogens. This extra time ensures your entire hand is covered and allows the scrubbing motion to detach bacteria from your hands and be picked up by soap and water.
