Soap is a substance that is typically composed of sodium or potassium salts of fatty acids. It is created through a process called saponification, where fats or oils react with an alkali, such as sodium hydroxide or potassium hydroxide. This chemical reaction produces soap molecules.
Soap molecules have a unique structure with a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail. When soap is mixed with water, it forms micelles, which are tiny clusters with the hydrophilic heads facing outward and the hydrophobic tails pointing inward.
When you spread soap over your hands, the hydrophilic heads of the soap molecules attract water, while the hydrophobic tails attach to dirt, oil, and germs on your skin. As you rub your hands together, the soap molecules surround and encapsulate these contaminants, forming structures called micelles. These micelles suspend the dirt and germs in water, allowing them to be easily rinsed away when you wash your hands.
Soap itself does not kill germs directly; it helps in their removal. The mechanical action of scrubbing and rinsing, combined with the soap's ability to bind to the contaminants, helps to dislodge and remove germs from your skin, reducing their population and the risk of transmission.
The exact origins of soap are difficult to pinpoint, but evidence suggests that it has been used for thousands of years. Ancient civilizations such as the Babylonians, Egyptians, and ancient Greeks were known to have produced soap-like substances. The earliest recorded evidence of soap production comes from ancient Babylon around 2800 BCE, where a clay tablet mentioned a soap-like material made from animal fats and wood ash. The ancient Romans also had a form of soap made from tallow and ashes. Soap-making techniques further evolved over time, and by the Middle Ages, soap production became more widespread in Europe.