Gaseous methane is compressed polytropically by a piston from 250C and 0.80 bar to a pressure of 5.0 bar. Assuming an index of compression of 1.2, calculate the change of entropy and work done, per unit mass of the gas. The relative molecular mass of methane is 16 and = 1.30. (

Asteam is contained in a rigid tank with a volume of 1 m3. initially, the pressure and temperature are 7 bar and 500 oc, respectively. the temperature drops due to cooling process. determine: (1) the temperature at which condensation begins in °c, (2) the fraction of the total mass that has condensed when the pressure decreased to 0.5 bar. (3) the volume in m3 occupied by saturated liquid at the final state?