21-09-2017, 01:04 AM
21-09-2017, 10:07 AM
In chemistry, a soap is a salt of a fatty acid. Domestic uses for soaps include washing, bathing and other types of cleaning, where soaps act as surfactants, emulsifying the oils to allow them to be carried by the water. In the industry they are also used in textile spinning and are important components of some lubricants. Metal soaps are also included in the oil paints formulations of modern artists as a rheology modifier.
Cleaning soaps are obtained by treating vegetable or animal oils and fats with a strong base, such as sodium hydroxide or potassium hydroxide in an aqueous solution. Fats and oils are made up of triglycerides; three molecules of fatty acids bind to a single molecule of glycerol. The alkaline solution, often called bleach (although the term "bleach soap" refers almost exclusively to soaps made with sodium hydroxide), induces saponification.
In this reaction, the triglyceride fats are first hydrolyzed to free fatty acids, and then these are combined with the alkali to form raw soap: an amalgam of various soap salts, excess fat or alkali, water and released glycerol (glycerin). Glycerin, a useful byproduct, can remain in the soap product as a softening agent, or it can be isolated for other uses.
Soaps are key components of most lubricating greases, which are typically calcium soap or lithium soap and mineral oil emulsions. Many other metallic soaps, including those of aluminum, sodium and mixtures thereof, are also useful. Such soaps are also used as thickeners to increase the viscosity of the oils. In ancient times, lubricating fats were made by adding lime to olive oil.
It can be understood in the following video: