1. Thermodynamics

2. Free Energy When a system changes energy, it can be related to two factors; heat change and positional/motion change. The heat change is the enthalpy change. The positional/motion change is the entropy. When a process occurs there is a total amount of energy transferred which is the free energy. If the total free energy change is negative, then the process can occur on its own without outside interference. This is a spontaneous process.

3. Spontaneity If a process is spontaneous in one direction, then it is non spontaneous in the reverse direction. Thermodynamic properties tell us nothing about the rate at which the reaction occurs. Reversible processes are processes that can be restored to their original state exactly by reversing the process. All spontaneous reactions are irreversible since it takes work from the surroundings to get it back.

4. Entropy Entropy can be looked at as either the randomness or freedom of motion of particles. It is a state function, so the entropy change can be determined from the initial and final states. Particles that have more locations that they can occupy, and more freedom to move have increasing entropy. This is clearest in phase changes as the entropy increases as you go from solid to liquid to gas or when you dissolve a solid. Entropy also increases when you have larger molecules.

5. Free energy and Entropy When ∆G is negative, it means there is a release of energy. That energy goes into the universe raising the randomness of the universe. If the process is reversible then there is no net change to the universe so your free energy change is zero. The second law of thermodynamics states that the entropy of the universe is unchanged in a reversible process, and increases for an irreversible process.

6. Isothermal Conditions Isothermal conditions are where you have a reversible process at a specific temperature. Phase changes are examples of reversible isothermal processes. All the energy going into the system to melt

7. Free Energy  G =  H - T  S sys If we divide by –T -  G = -  H +  S sys -  H =  S surr T T T -  G =  S surr +  S sys =  S univ at constant T, P T At what value of  G, is  S univ > 0 or “spontaneous”