What is Soap?
“True Soap”
…chemistry…
Saponification
As defined by the U.S. Food and Drug Administration:
“The bulk of the nonvolatile matter in the product consists of an alkali salt of fatty acids (i.e., the material you get when you combine fats or oils with an alkali such as lye).”
This means that “soap” is a material created through the saponification of oils or fats with a strong alkaline (basic, pH >7) compound, such as lye (NaOH).
Chemistry is all about combining two or more things together and studying how that reacts and creates one or more “new” things after the reaction. Once you understand HOW the reaction is happening (i.e. which molecules are moving where, and WHY), you can predict and plan, and ideally, utilize ALL the materials so that none are wasted.
My favorite chemistry analogy (from my high school chemistry teacher Mr. Zeise):
You want to create a sandwich, just one sandwich from several individual ingredients.
2 slices of bread + 1 scoop peanut butter + 1 scoop grape jelly
= 1 peanut butter and jelly sandwich
Missing any one of those ingredients would NOT result in a PB&J sandwich; it would make “something", but not the true PB&J.
Several parts together, CAN be considered one, new entirely definable thing.
Congratulations! You have just walked through “stoichiometry”, which is the way that chemists write out chemical compounds and predict what will result and how much is used or created.
This is a chemistry word, yes, but humans have been mixing up “soap” even without rationalizing the reaction with modern chemistry nomenclature.
Treating an animal fat (e.g. beef tallow) or vegetable oil (e.g. olive oil) with a strong alkaline, like lye (sodium hydroxide, NaOH), will result in a chemical reaction occurring. This process is called “saponification”, and the reaction leaves behind “fatty acid salts” (the thing we call “soap”), and an alcohol.
Common Soap Ingredients
Common fats/oils used in soap-making, and their resulting “fatty acid salt” after saponification with lye (sodium hydroxide) :
Olive Oil → Sodium Olivate
Coconut Oil → Sodium Cocoate
Palm Oil → Sodium Palmate
Shea Butter → Sodium Shea Butterate
Lard → Sodium Lardate
Tallow → Sodium Tallowate