Air is compressed in a piston–cylinder system having an initial volume of 80 in³. The initial pressure and temperature are 20 psia and 140 F. The final volume is one-eighth of the initial volume at a pressure of 175 psia. Determine the following:

A. The final temperature (F)
B. The mass of air (lb_m)
C. The change in internal energy (Btu)
D. The change in enthalpy (Btu)
E. The change in entropy (Btu/lb_m·R)