A gas is sealed in a container with rigid walls that allow heat to flow through them. A thermal process takes place on the gas. What would be the best model for the type of process?
Such a process can be modeled as an isothermal process at constant volume. The Helmholtz free energy F = E - T S will tend to decrease in such a process, and the maximum amount of work that can be extracted from the system is less than the drop in F.
