soap

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Offline murshida

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soap
« on: May 16, 2018, 03:51:40 PM »
Soap is the term for a salt of a fatty acid[1] or for a variety of cleansing and lubricating products produced from such a substance. Household uses for soaps include washing, bathing, and other types of housekeeping, where soaps act as surfactants, emulsifying[2] oils to enable them to be carried away by water. In industry, they are used as thickeners, components of some lubricants, and precursors to catalysts.
Kinds of soaps
Since they are salts of fatty acids, soaps have the general formula (RCO2−)nMn+ (R = alkyl). The major classification of soaps is determined by the identity of Mn+. When M = Na or K, the soaps are called toilet soaps, used for handwashing. Many metal dications (Mg2+, Ca2+, and others) give metallic soap. When M = Li, the result is lithium soap (e.g., lithium stearate), which is used in high-performance greases.[3]

Non-toilet soaps
Soaps are key components of most lubricating greases and thickeners. Greases are usually emulsions of calcium soap or lithium soap and mineral oil.[4] Many other metallic soaps are also useful, including those of aluminium, sodium, and mixtures thereof. Such soaps are also used as thickeners to increase the viscosity of oils. In ancient times, lubricating greases were made by the addition of lime to olive oil.[5]

Metal soaps are also included in modern artists' oil paints formulations as a rheology modifier.[6]

Production of metallic soaps
Most heavy metal soaps are prepared by neutralization of purified fatty acids:

2 RCO2H + CaO → (RCO2)2Ca + H2O
Toilet soaps
In a domestic setting, "soap" usually refers to what is technically called a toilet soap, used for household and personal cleaning. When used for cleaning, soap solubilizes particles and grime, which can then be separated from the article being cleaned. The insoluble oil/fat molecules become associated inside micelles, tiny spheres formed from soap molecules with polar hydrophilic (water-attracting) groups on the outside and encasing a lipophilic (fat-attracting) pocket, which shields the oil/fat molecules from the water making it soluble. Anything that is soluble will be washed away with the water.
https://en.wikipedia.org/wiki/Soap