A well-insulated rigid tank contains 20 kg of saturated liquid-vapor mixture of water at a 100 kPa. Initially, 73.72% of the mass is in the liquid phase. An electric heater inside is turned on and kept on until all the liquid vaporized. Determine:
a) The entropy change of the water during this process
b) The work done by the electric heater during this process H2O 2 kg