1. Using the differential forms of the thermodynamic potentials 9.15, and the second law constraints 9.1, prove that for two interacting systems in equilibrium:
(a) the Helmholtz free energy is a minimum if the interaction is isothermal;
(b) the enthalpy is a maximum if the interaction is isobaric.
(c) The Gibbs free energy is a minimum if the interaction is both isothermal and isobaric.
2. Explain why Helmholtz free energy is really only the "work function" for certain types of processes.
3. Explain why the enthalpy is really only the "heat function" for certain types of processes.