Entropy and Irreversibility

This lecture discusses the concept of entropy and its connection to irreversible processes, exploring the transition from reversible to irreversible cycles and expressing the second principle in terms of entropy. It demonstrates the equivalence of the second principle with Clausius' non-sets, starting from defining the entropy state function and its calculation for real gases. The lecture covers the calculation of total heat exchange along reversible transformations using the Ts diagram, illustrating how for reversible cycles, the total entropy change is zero, while for irreversible cycles, it is greater than zero. Through examples involving piston-cylinder systems, the instructor explains the work done by gases in different scenarios, emphasizing the significance of reversible cycles in understanding thermodynamic processes.