The heat of reaction is always positive for an exothermic reaction. The Law of Conservation of energy says the energy in the universe is constant. A spontaneous reaction is one that produces an explosion 8. Entropy, S, increases when disorder increases. Free energy is the energy available from a reaction that can be used for other purposes.
Activation energies are high for slow reactions.
Reactions occur more slowly if the temperature is raised. A reaction with an activation energy of 35000 calories is low and the reaction is fast. Entropy is always increasing. It is not governed by a conservation law. Reaction rates increase when the concentration of reactants increases 16.