C. Air (ideal gas) is contained in a piston/cylinder arrangement, that can exchange heat with a reservoir at a temperature of 25 °C. The amount of air is 1 kg and it is initially at a temperature of 25 °C and a pressure of 105 kPa. Then air is isothermally compressed to a pressure of 300 kPa.

1 x 10 ° mm3 of air at a pressure of 10 bar and temperature 300°C, expands 10 times its original volume and its final temperature will be 25°C. Calculate (1) mass (ii) change in entropy by considering temperature, volume, entropy relationship (iii) change in entropy by considering temperature, pressure, entropy relationship (iii) change in entropy by considering pressure, volume, entropy relationship. Gas Molecular weight (M) (kJ/kg K) (kJ/kg K) Air 28.97 1.005 0.718 Oxygen Nitrogen Hydrogen Carbon monoxide 32 0.920 0.660 28 1.046 0.754 14.40 10.40 28 1.046 0.754