A piston-cylinder device contains 0.78 kg of nitrogen gas at 140 kPa and 37°C. The gas is now compressed slowly in a polytropic process during which PV.S = constant. The

process ends when the volume is reduced by one-half. Determine the entropy change of nitrogen during this process. The gas constant of nitrogen is R= 0.2968 kJ/kg-K. The constant volume specific heat of nitrogen at room temperature is cy= 0.743 kJ/kg-K. (Round the final answer to five decimal places. The entropy change of nitrogen during this process is --------kJ/K.