ELI5- What is “soap”? We have bar soap, dish soap, antibacterial soap like dial, hand soap, foaming hand soap and more I’m sure. What ties them together to all be called soap?
In: Chemistry
Soap is a salt of a fatty acid.
A fatty acid is (in ELI5 terms) a molecule which has a bit of oxygen on one end attached to a loooong chain of carbon and hydrogen.
A salt is a compound where a negatively-charged molecule and a positively-charged molecule link up together. In this case, the negative charge is on the fatty acid; the positive molecule is generally sodium or potassium in household soaps, but can be calcium, lithium, aluminum, or many others.
Because soap is defined by these long-tail molecules which are special on one end, they have special properties. The tail likes to attach to oils; the other end likes to attach to water. This makes it cluster around droplets of oil and other dirty stuff and isolates them, which makes them easy to wash away.
Beyond that, you can add other materials to change a soap’s properties and thus its type. Using different oils can make your soap liquid rather than solid, a special dispenser makes it foam up, you can introduce air bubbles into your bar to make it have different physical properties, you can add a disinfectant to get antibacterial soap.
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