Chemistry of a Soap Bar
As a kid, using soap might have seemed magical. You lather it up and -- presto! Bubbles appear while dirt disappears. However, the real magic behind soap is a little more involved than that. Plant and animal ingredients form some of the basic building blocks of bar soap. The sources' fats or oils are combined with an alkali, such as sodium salt, resulting in a chemical reaction that creates true soap as a by-product, along with water and glycerin [source: The Soap and Detergent Association].
When it comes to how soap actually cleans your skin, think of it as a matchmaker of sorts. If you've ever tried to just rinse off with just plain water, you've probably noticed that it doesn't usually work very well. This happens because of surface tension that keeps water from spreading across the skin. You need some sort of cleansing product to remove dirt, excess oil and other impurities from your skin. That's where soap comes in.
At the molecular level, the true soap that's produced when fat and alkali react contains a hydrocarbon chain, which is basically just a strand of hydrogen and carbon atoms. One end is hydrophobic, which means it repels the water and is attracted to the dirt and oil on your skin. The other end is hydrophilic, which is attracted to water. When you lather up, the hydrophobic end attaches to all those unwanted impurities, and the hydrophilic end grabs hold of the water. This process allows the water to easily rinse away the dirt and oil, leaving you with clean, fresh skin.
But that isn't the only cleanser out there. Read on to see how the chemistry of non-soap products is different from soap.