I'm 16. I study chemistry in college along with biology, physics, and maths, and I have a general interest in all of them.
I always found this interesting: sometimes when I left the bathtub, even when I forgot to use soap, the bath would still have a somewhat noticeable, murky tint in the water, indicating that something had dissolved in it, even though I didn't take the time to rub it off manually. When we get in the bath, how does the dirtiness (small amounts of mud, bacteria, pen markings etc.) dissolve in the bath alone without any of our skin dissolving as well so that we can leave clean? Maybe dead skin might dissolve, that would make sense, is there an adaptive mechanism on the skin involved in this sort of process of hygiene? The same thing would happen if I put any other object in the water with something on its surface and the object would come out clean when the thing on the surface dissolved.
How does the water break the attraction? Some sort of cohesive force, between the atoms/molecules of the thing (dirtiness) on the surface of the object and the atoms/molecules of the object (our bodies) and separate them to make it dissolve? And how can it differentiate between the cohesion of the skin and the dirtiness (what determines solubility, if both polar and non polar molecules on our skin will dissolve in the water)?