Soap

Soap is a cleaning substance made from the mixture of fat or oil and an alkali (a strong base substance, for example sodium hydroxide). It helps remove grease and dirt clinging to skin, clothing, or dishes when mixed with water, something that cannot easily happen using water alone.

A soap molecule has two distinct sides: a water-loving side (hydrophilic) and a fat-loving side (hydrophobic). The fat-loving side attaches to grease particles, while the other side is pulled toward water. For this reason fat breaks apart into tiny droplets suspended in water, which can then be rinsed away.

How soap is made

The basic process is called saponification: fat (a triglyceride) is combined with an alkali, producing a mixture of fatty acid salts (which is soap) and glycerol. Sodium hydroxide produces hard soap; potassium hydroxide produces soft or liquid soap. The fats used include plant oils such as coconut oil and olive oil, as well as animal fats.

Soap and modern products

Today most laundry products are not true soap, but detergents made from petroleum or oils. An advantage of detergent is that it does not easily interact with hard water containing many minerals, whereas ordinary soap forms white scum in hard water that sticks to clothing.

Health

Handwashing with soap and water is considered one of the simplest steps to reduce the spread of gastrointestinal and respiratory diseases. Soap breaks down the fatty outer layer surrounding certain viruses, destroying them.