A pistoncylinder device initially contains 15 ft3 of helium gas at 25 psia and 70F. Helium is

Question:

A piston–cylinder device initially contains 15 ft3 of helium gas at 25 psia and 70°F. Helium is now compressed in a polytropic process (PVn = constant) to 70 psia and 300°F. Determine
(a) The entropy change of helium,
(b) The entropy change of the surroundings, and
(c) Whether this process is reversible, irreversible, or impossible. Assume the surroundings are at 70°F.