Carbon dioxide of mass 0.9 kg is contained in a vessel at a pressure of 4 MPa and a temperature of 500 °C. The gas is allowed to expand into an empty connected vessel, during which its temperature falls to 120 °C. The combined volume of the two vessels is 0.45 m3. Determine (i) the initial volume of the carbon dioxide, (ii) its final pressure and (iii) the polytropic index ‘n’ of the expansion process. Carbon dioxide has a molecular weight of 44 and the universal gas constant is 8314 Jkmol-1K-1.

Carbon dioxide of mass 0.9 kg is contained in a vessel at a pressure of 4 MPa and a
temperature of 500 °C. The gas is allowed to expand into an empty connected vessel, during
which its temperature falls to 120 °C. The combined volume of the two vessels is 0.45 m3.
Determine (i) the initial volume of the carbon dioxide, (ii) its final pressure and (iii) the
polytropic index ‘n’ of the expansion process. Carbon dioxide has a molecular weight of 44 and the universal gas constant is 8314 Jkmol-1K-1.