Assume that 1 mole of an ideal van der Waals fluid is expanded isothermally, at temperature Th, from an initial volume Vi to a final volume Vf. A thermal reservoir at temperature Tc is available. Apply equation 4.9 to a differential process and integrate to calculate the work delivered to a reversible work source. Corroborate by overall energy and entropy conservation.
Hint: Remember to add the direct work transfer PdV to obtain the total work delivered to the reversible work source (as in equation 4.9).