V.(15 points) The equation of state for a Berthelot gas is: P= ORT na V-nb TV where a and b are constants that depend on the identity of the gas. a) Derive an expression for the work done by or on one mole of a Berthelot gas undergoing a reversible, isothermal expansion/compression from V, to V, at temperature T. b) Derive an equation for the entropy change for the same process in part a)