Problem on Clausius equation of state

Question

If a gas can be described by the Clausius equation of state:

P (V-b) = RT

Where b is a constant, then:
 
(a) Obtain an expression for the residual volume.
 
(b) Obtain an expression for the residual enthalpy.
 
(c) Obtain an expression for the residual entropy.
 
(d) Calculate the enthalpy and entropy of the gas at 40 ^oC, 25 bar if b = 1 x 10^-4 m³/mol. At 25 ^oC and 1 bar H and S = 0. For simplicity, let’s assume C_p = 35 J/mol/K and is constant.