Curiosity Corner: How does soap remove dirt?

Soap is something that each of us uses every day, when we wash our hands or dishes or take a bath, and yet few of us think about how soap actually works. Cleaning with water can’t always clean grease from surfaces, but soap makes it simple and easy to clean. "Everyday Cleaning Chemistry: Soap" shows how soap cleans by using chemistry that captures dirt and removes it while cleaning. The chemistry of soap and dirt shows why washing hands is crucial for hygiene and cleanliness.Water alone can’t remove greaseThe reason for dirt and germs clinging to our skin in most cases is due to the presence of oil and grease. Water molecules are attracted to water molecules but not to oil molecules. This makes it difficult for dirt containing oil to go away just by washing it off with water. This is where soap comes into action, which acts like a bridge for water and oil.Two-sided structure of a soap moleculeEach soap molecule has a distinct shape that is composed of two different parts. One part loves water, and the other part loves oil and grease. When you mix the soap with water, the parts that like oil stick to the dirt and grease, and the parts that like water stick to the water. Thus, the clever shape of the soap molecule allows the soap to pick up dirt that the water alone cannot.Dirt gets trapped inside micellesWhen you apply soap on your hands, the soap molecules enclose the dirt and grime, forming small pockets that resemble bubbles and are called micelles. Dirt and bacteria are locked away inside the micelles. The water-attracting parts of the molecules face outward so that the micelles remain suspended within water. Dirt is now unable to stick to skin.Rinsing washes dirt awayNow, the dirt can be trapped in the micelles. When water is poured on the dirt trapped in micelles, it becomes easy to remove the dirt from the surface of the skin. When dirt is trapped in micelles, it becomes easy to rinse it off. Otherwise, the dirt will be caught in micelles but will still be in the skin or surface.Soap also helps remove germs Soap removes dirt, but it can also help eliminate germs. This is because most germs contain oily materials surrounding them. Soap can easily degrade these materials, hence eliminating the germs. That is why it is advised that hands be washed with soap, specifically prior to eating a meal and after visiting the restroom. A piece of soap can be an important tool in our lives if we want to stay healthy.