what i just wrote before about the combinatorial complexity of states, this is even more the case as we are talking about the positions of gazillions of molecules and tehir associated particles (photons, electrons, protons, etc etc)

they only become predictable given control of their mixing within specific narrow conditions of their state space

reaction equilibrium, for example, relates to the level of energy lost in the transformation, and the energy required to undo this transformation - if you put too much energy in, it can go to other states instead

again, some of it doesn't do all the same thing, this is why purification is always a key step in chemistry... even 0.1% contamination can completely stop a reaction from taking place