Soaps & Detergents: Chemistry chemistry To understand what is needed to achieve eﬀecve cleaning, it is helpful to have a basic knowledge of soap and detergent chemistry. surfacetensionWater, the liquid commonly used for cleaning, has a property called surface tension. In the body of the water, each molecule is surrounded and aracted by other water molecules. However, at the surface, those molecules are surrounded by other water molecules only on the water side. A tension is created as the water molecules at the surface are pulled into the body of the water. This tension causes water to bead up on surfaces (glass, fabric), which slows weng of the surface and inhibits the cleaning process. You can see surface tension at work by placing a drop of water onto a counter top. The drop will hold its shape and will not spread. surfactantIn the cleaning process, surface tension must be reduced so water can spread and wet surfaces. Chemicals that are able to do this eﬀecvely are called surface acve agents, or surfactants. They are said to make water "weer." Surfactants perform other important funcons in cleaning, such as loosening, emulsifying sinkdishes(dispersing in water) and holding soil in suspension unl it can be rinsed away. Surfactants can also provide alkalinity, which is useful in removing acidic soils. 04ChemSurfactants are classiﬁed by their ionic (electrical charge) properes in water: anionic (negave charge), nonionic (no charge), caonic (posive charge) and amphoteric (either posive or negave charge). Soap is an anionic surfactant. Other anionic as well as nonionic surfactants are the main ingredients in today's detergents. Now let's look closer at the chemistry of surfactants. Soaps Soaps are water-soluble sodium or potassium salts of fay acids. Soaps are made from fats and oils, or their fay acids, by treang them chemically with a strong alkali.