What is soap made of?

Whether you are in the mall or at home, you can see all kinds of soaps. So, what kind of chemical substances are soap and what is soap made of?

Soap is a sodium salt of a carboxylic acid, R-CO2Na, where the R groups are generally different and are various hydrocarbon groups.

1. Soap is a general term for fatty acid metal salts. The general formula is RCOOM, where RCOO is a fatty acid radical, and M is a metal ion. The carbon number of fatty acids in daily soaps is generally 10-18, the metals are mainly alkali metals such as sodium or potassium, and ammonia and some organic bases such as ethanolamine and triethanolamine are also used to make special-purpose soaps.

2. In a broad sense, fatty acid salts obtained by saponification or neutralization of oils, waxes, rosin, or fatty acids with alkalis can be called soaps. Soap is soluble in water and has the effect of washing and decontamination. There are various types of soap, also known as toilet soap, metal soap and compound soap.
3. The main component of soap is R-CO2Na, (sodium stearate (C17H35COONa)), in which R groups are generally different and are various hydrocarbon groups. R- is a hydrophobic group, and a carboxyl group is a hydrophilic group. In hard water, soap and Ca2+, Mg2+, etc. form curd-like substances, fatty acid calcium salts, etc., which are commonly referred to as “calcium soap” and become useless detergents. Adding softeners to hard water removes the hard water ions, allowing the soap to work. Medicated soap is mainly in which some disinfectants are added. The fragrance is added to the soap. Crystal soap has a particularly strong degreasing power due to its soap base.

The ingredients of soap are divided into main ingredients and additive ingredients.

1. Main components: various kinds of animal fats and vegetable oils are mixed, and the sodium fatty acid is generated after the caustic soda saponification reaction. This is the main body of the soap’s washing ingredients.
2. Additive ingredients: rosin, sodium silicate, CMC… These ingredients can improve the hardness of the soap, increase the foam, and increase the decontamination ability of the soap.