An isothermal turbine is used to expand a stream of fluid flowing at 1 mol/s from (300 K, 40 bar) to (300 K, 1 bar). The process is at steady state and is completely reversible. Compute the shaft power of the turbine if: (a) The stream is methane (CH4) and can be treated as an ideal gas. (b) The stream is methane gas but is non-ideal. The residual properties can be estimated by the Pitzer B correlation, with the parameters T = 190.6 K, P = 45.99 bar, and w = 0.012. (c) The stream is liquid water and can be treated as an incompressible liquid with density p = 1 kg/L. The ideal-gas constant-pressure heat capacity for methane is C = 4.2R, independent of temperature. The heat capacity for liquid water is Cp = 9.1R, independent of temperature or pressure.