Question about reactions that are always spontaneous and non spontaneous
I was thinking about the boiling of water


That is a good example of a process that goes forward at higher temperature (water boils when heated above the normal boiling point) and goes in the opposite direction at lower temperature (steam condenses below the normal boiling point). This process also depends on the pressure, but my statements are valid at atmospheric pressure.

For this process, the entropy change is positive (water has more freedom to move in the gas phase compared to the liquid phase) and the enthalpy change is positive (endothermic, it takes energy to break the hydrogen bonds between water molecules).


  Reactions that are always spontaneous


How about combustion of cyclohexane? The entropy change is positive (lots of gas molecules are formed - six carbon dioxide molecules per hexane) and the enthalpy change is negative (exothermic).


  Reactions that are always non-spontaneous


Once you are certain that a reaction is always spontaneous, it is easy to find one that is always non-spontaneous - just swap reactants and products. So according to this argument, cyclohexane and oxygen will never form from carbon dioxide and water spontaneously. That sounds reasonable.