Why do did some liquids (chemicals) mixed together and others did not?
I assume you’re talking about why some chemicals when mixed react and some don’t. The answer is found with enthalpy and entropy. Enthalpy is a measure of a reactions gain or loss of energy. If a reaction has a negative enthalpy change (losing energy) then the products will be more stable and have stronger bonds than the reactants. This means that when you mix the two reactants together in such an equation they will probably react together. However the other factor affecting whether two chemicals will react with each other is entropy. Entropy is a measure of the randomness or disorder of a system. It is more likely that units in a system will become chaotic rather than organized so if the products of a reaction are more random than the reactants then the reaction is likely to happen. e.g. melting ice gives the molecules more entropy because they are changing from an ordered ice crystal to chaotic molecule in a liquid which move around at random.
