Soap

Soap is a cleaning agent that is composed of one or more salts of fatty acids. It is used in conjunction with water for washing and cleaning. It may also be used in artisanal or industrial contexts, to process, clean, or finish objects and surfaces. Soap has been made for at least 5000 years, with the earliest evidence of soap-making traced back to ancient Babylon.

History

The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BC in ancient Babylon. A formula for soap consisting of water, alkali, and cassia oil was written on a Babylonian clay tablet around 2200 BC. The Ebers papyrus (Egypt, 1550 BC) indicates the ancient Egyptians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance.

Composition

Soap is created by the chemical reaction of a fatty acid with an alkali. A soap is a salt of a compound, known as a fatty acid. A soap molecule has a long hydrocarbon chain with a carboxylic acid group on one end, which has ionic bond with a metal ion, usually a sodium or potassium. The hydrocarbon end is nonpolar, which is highly soluble in nonpolar substances like oils, fats, and grease.

Production

Soap is produced industrially in four basic steps. This includes saponification, glycerin removal, soap purification, and finishing. Soap production in the industrial setting can be broken down into continuous or batch processes.

Uses

Soap is used for a variety of purposes, from personal hygiene to laundry and industrial uses. It can be used as a cleaning agent, a foaming agent, and even as a surfactant.

Health and environmental effects

While soap is generally considered safe for human use, it can cause problems if it gets into the eyes or is swallowed. Some soaps are also harmful to the environment, particularly those that contain certain chemicals or are not biodegradable.

See also

• Detergent
• Hand sanitizer
• Hygiene
• Saponification

Soap Resources
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