A refrigerator with a coefficient of performance of COP = 4, requires 20 kJ of mechanical work to operate in each cycle. a) Where does the refrigerator obtain the mechanical

work (energy) from? b) How much heat is absorbed from the low temperature reservoir during each cycle? How much heat does the refrigerator discard to the high temperature reservoir during each cycle? Use the ideal gas equation to determine the number of moles of a gas compressed to 3 x atmospheric pressure, if the volume is measured to be 2.4x10-3 m³ at a temperature of310 K. (Assume that the universal molar gas constant R =8.31 J mol-1 K-l and that atmospheric pressure is P atm = 1.01 x 105PA) The same sample of gas is allowed to expand iso thermally until the pressure reaches 2.5times the atmospheric pressure. Calculate the new volume of the gas.