I would like to start today explaining in easy words how soap cleans. We use it everyday. Have you ever thought how this substance works?
How soap cleans?
There are substances that can be dissolved in water (for example salt), and others that cannot (for example oil). Water and oil do not mix together, so if we try to clean an oily stain from a cloth or from the skin, water is not enough. We need soap.
Soap is formed by molecules with a "head" that likes water (hydrophilic) and a long chain which hates it (hydrophobic):
Because of this dualism, soap molecules act like a diplomat, improving the relationship between water and oil. How? When soap is added to the water, the hydrophilic heads of its molecules stay into the water (they like it!), while the long hydrophobic chains join the oil particles and remain inwards (escaping from the water). In that way, they form circular groups named micellas, with the oily material absorbed inside:
An emulsion of oil in water is then formed, this means that the oil particles become suspended and dispersed into the water. Thus, those oil particles are liberated from the cloth or the skin, and the emulsion is taken away with the rinsing.
In summary, soap cleans by acting as an emulsifier. It allows oil and water to mix so that oily grime can be removed during rinsing. There are more things involved in this process, but this is the general idea.