A mass of 7 kg of helium undergoes a process from an initial state of 3 m3/kg and 27 ^o C to a final state of 0.6 m3/kg and 95 ^o C. Assume the process is reversible and helium can be treated as an ideal gas, determined the entropy change of helium. The constant-volume specific heat of helium is cv = 3.1156 kJ/kg· K.